I

!

NBSIR 76-843 (/

I • FILE OOP

; MU .• • • •- LIQUEFIED NATURAL GAS RESEARCH

at the

NATIONAL BUREAU OF STANDARDS

PROGRESS REPORT FOR THE PERIOD

*~

1 JANUARY-30 JUNE, 1976

D.E. Diller, Editor

CRYOGENICS DIVISION • N BS-I N STITUTE FOR BASIC STANDARDS • BOULDER, COLORADO

NBSIR 76-843 (

LIQUEFIED NATURAL GAS RESEARCH

at the

NATIONAL BUREAU OF STANDARDS

D.E. Diller, Editor

Cryogenics Division

Institute for Basic Standards

National Bureau of Standards

Boulder, Colorado 80302

Progress Report for the Period

1 January — 30 June, 1976

U.S. DEPARTMENT OF COMMERCE, Elliot L. Richardson, Secretary

Edward 0. Vetter, Under Secretary

Dr. Betsy Ancker-Johnson , Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Acting Director
Prepared for:

American Gas Association, Inc.

1515 Wilson Boulevard

Arlington, Virginia 22209

LNG Density Project Steering Committee

(in cooperation with the American Gas Association, Inc

Pipeline Research Committee

(American Gas Association, Inc.)

Federal Power Commission

Bureau of Natural Gas

Washington, DC 20426

U. S. Department of Commerce

Maritime Administration

Washington, DC 20235

U. S. Department of Commerce

National Bureau of Standards

Institute for Basic Standards

Boulder, Colorado 80302

U. S. Department of Commerce

National Bureau of Standards

Office of Standard Reference Data

Washington, DC 20234

U. S. Department of Commerce

National Bureau of Standards

Office of International Standards

Washington, DC 20234

LNG Sampling Measurements Supervisory Committee

National Aeronautics and Space Administration

Lewis Research Center

Cleveland, Ohio 44135

American Bureau of Shipping

45 Broad Street

New York, NY 10004

ii
ABSTRACT

Twenty-two cost centers supported by six other agency sponsors in

addition to NBS provide the basis for liquefied natural gas (LNG) research

at NBS. During this six month reporting period the level of effort was at

a 20 man-year level with funding expenditures of over $600,000. This

integrated progress report to be issued in January and July is designed to:

1) Provide all sponsoring agencies with a semi-annual and an annual

report on the activities of their individual programs.

2) Inform all sponsoring agencies on related research being con- ducted at the Cryogenics Division of NBS-IBS.

3) Provide a uniform reporting procedure which should maintain

and improve communication while minimizing the time, effort

and paperwork at the cost center level.

The contents of this report will augment the quarterly progress meetings of some sponsors, but will not necessarily replace such meetings.

Distribution of this document is limited and intended primarily for the

supporting agencies. Data or other information must be considered pre- liminary, subject to change and unpublished; and therefore not for citation

in the open literature .

Key words: Cryogenics; liquefied natural gas; measurement; methane;

properties; research.
CONTENTS

Cost Center Page

I. REFERENCE DATA

a) THERMOPHYSICAL PROPERTIES DATA FOR PURE 1 COMPONENTS OF LNG MIXTURES (American 2750574

Gas Association, Inc.)

b) FLUID TRANSPORT PROPERTIES 2750124 4 (NBS-Office of Standard Reference Data)

c) PROPERTIES OF CRYOGENIC FLUIDS 2750141 5 (NBS)

d) PROPERTIES OF CRYOGENIC FLUID MIXTURES 2750142, 7 (NBS; NBS-Office of Standard Reference 2750145

Data; NASA; A.G.A.) 2750548 and

2754574

e) DENSITIES OF LIQUEFIED NATURAL GAS MIX- 2751574 9 TURES (LNG Density Project Steering and

Committee - AGA) 2 7 52 574

f) LOW TEMPERATURE MATERIAL BEHAVIOR 2 7 504 30 12

(Maritime Administration)

g) PROGRAM FOR REDUCING THE COST OF LNG 2751430 14 SHIP HULL CONSTRUCTION — PHASE II 2752430

SHIP STEEL IMPROVEMENT PROGRAM (Mari- 2753430

time Administration)

II. MEASUREMENT SCIENCE

a) CUSTODY TRANSFER - LNG SHIPS 2750460 16

(Maritime Administration)

b) HEATING VALUE OF FLOWING LNG (Pipeline 2756579 19

Research Committee - AGA)

c) LNG DENSITY REFERENCE SYSTEM 2757574 2 3 (American Gas Association, Inc.; and

National Bureau of Standards) 2750161

d) LNG SAMPLING MEASUREMENT STUDY (LNG 2750575 24

Sampling Measurements Supervisory

Committee

)

III. TECHNOLOGY TRANSFER

a) SURVEY OF CURRENT LITERATURE ON LNG 2 5 AND METHANE (American Gas Association, 2759 574

Inc. )

b) LIQUEFIED NATURAL GAS TECHNOLOGY 2750403, 27

TRANSFER (Maritime Administration; 2751403,

American Gas Association, Inc.; 2752403,

American Bureau of Shipping) 2750570,

2754574 and

2758574

C) OIML JOINT SECRETARIAT ON LNG MEASURE- 2750104 29

MENTS (American Gas Association, Inc.;

NBS-Office of International Standards;

NBS-Cryogenics Division)

iv
Contents (continued) Page

III. TECHNOLOGY TRANSFER (continued)

d) FEDERAL POWER COMMISSION CONSULTATION 2750404 31

(FPC)

IV. APPENDICES

A. Fracture Behavior of the Heat Affected Zone A~l

in 5% Ni Steel Weldments, H. I. McHenry and

R. P. Reed.

v

1. Title. THERMOPHYS-I CAL PROPERTIES DATA FOR PURE COMPONENTS OF LNG

MIXTURES

Principal Investigators. R. D. Goodwin, H. M. Roder , and R. Tsumura*

.

2. Cost Center Number . 2750574

3. Sponsor Project Identification . American Gas Association, inc.

Project BR-50-10.

4. Introduction . Accurate phase equilibrium, equation of state (PVT)

,

and thermodynamic properties data are needed to design and optimize

gas separation and liquefaction processes and equipment. Accurate

data for the pure components of LNG mixtures will permit developing

comprehensive accurate predictive calculation methods which take

into account the dependence of the thermophysical properties of mixtures on the composition, temperature, and density.

This project will provide comprehensive accurate thermophysical

properties data and predictive calculation methods for compressed and

liquefied hydrocarbon gases to support the development of LNG technology at NBS and throughout the fuel gas industry.

5. Objectives or Goals . The objectives of our work are the determination

of comprehensive accurate thermophysical properties data and predictive

calculation methods for the major pure components (methane, ethane,

propane, butanes, and nitrogen) of liquefied natural gas mixtures at

temperatures between 90 K and 300 K and at. pressures up to 350 bar

(5000 psi) . Our goal is to provide a range and quality of data that

will be recognized as definitive or standard for all foreseeable low

temperature engineering calculations

.

6. Background . Liquefied natural gas is expected to supply an increasing

percentage of the United States' future energy requirements. It is

likely that massive quantities of liquefied natural gas will be

imported during the years 1976 - 1990. Ships and importation terminals

are being built for transporting, storing, and vaporizing liquefied

natural gas for distribution. Accurate physical and thermodynamic

properties data for compressed and liquefied natural gas mixtures are needed to support these projects. For example, accurate compressibility

and thermodynamic properties data are needed to design and optimize

liquefaction and transport processes; accurate data for the heating

value, which for liquefied natural gas mixtures depends on the total

volume, the density, and the composition, are needed to provide a basis for equitable custody transfer.

Accurate thermodynamic properties data for liquefied gas mixtures must

be based on precise compressibility and calorimetric measurements;

compressibility data give the dependence of thermodynamic properties on pressure and density (at fixed temperatures); calorimetric data give

the dependence of thermodynamic properties on temperature (at fixed

pressures and densities). It is impossible, however, to perform enough

compressibility and calorimetric measurements directly on mul ticomponent

mixtures to permit accurate interpolation of the data to arbitrary

composition, temperatures and pressure. Instead, thermodynamic properties data for multicomponent mixtures usually must be predicted

(extrapolated) from a limited number of measurements on the pure com- ponents and their binary mixtures

.

Consejo Nacional de Ciencia y Tecnologia (CONACYT) Mexico City. Currently

a guest worker with the Cryogenics Division, National Bureau of Standards,

Institute for Basic Standards in Boulder, Colorado.
This project was initiated to provide the natural gas industry with

comprehensive accurate data for pure compressed and liquefied methane,

the most abundant component in LNG mixtures. We have published

National Bureau of Standards Technical Note 653, "Thermophysical

Properties of Methane, From 90 to 500 K at Pressures to 700 Bar," by

Robert D. Goodwin (April 1974). This report contains the most comprehensive and accurate tables available for the thermophysical properties

of pure gaseous and liquid methane, and provides an accurate basis for

calculating thermophysical properties data for LNG mixtures. Similar

data have now been obtained for compressed and liquefied ethane.

7 . Program and Results .

7.1 Ethane, Specific Heat Data — H. M. Roder

This phase of the program is essentially complete. Two manuscripts

describing the results of the research have been submitted for

publication

:

H. M. Roder, Measurements of the Specific Heats, C 0 and Cv of Dense

Gaseous and Liquid Ethane, submitted to J. Res. Nat. Bur. Stand. (US).

H. M. Roder, The Heats of Transition of Solid Ethane, to appear in the

August 15 issue of J. Chem. Phys. (1976).

7.2 Ethane, Sound Velocity Data — R. Tsumura

Measurements of the speed of sound in saturated liquid and compressed

fluid ethane have been made at a frequency of 10 MHz using the pulseecho technique. Measurements were made in the saturated liquid from

near the triple point to 280 K and in the compressed fluid along

selected isotherms from 100 to 320 K at pressures to about 35 MPa.

Preliminary analysis of the internal consistency of these data has

been made and the imprecision is estimated to be less than 0.05%.

Near the critical point, where the use of the pulse-echo technique was impossible, a new method, using the alignment of the leading edges of

the electrical pulse and the acoustical pulse, was employed, extending

the data in the saturated liquid up to 299 K and in the compressed

liquid to densities between 10 and 12 mol/1.

Some data were also obtained using the pulse-echo technique at a frequency of 1 MHz; the imprecision in the data is estimated to be less

than 0.1%. The agreement with the data at 10 MHz in the saturated

liquid in the range 160 to 299 K is within experimental error.

However, a systematically increasing disagreement has been observed

as the triple point is approached, reaching a maximum of 0.8% near this

point

.

7.3 Ethane, Thermophysical Properties Data — R. D. Goodwin

All computational work on the thermophysical properties of ethane has

been completed, employing new experimental physical properties data

from this laboratory. A manuscript "Thermophysical Properties of

Ethane, from 90 to 600 K at Pressures to 700 Bar," has been completed

and is being reviewed prior to publication as an NBS Technical Note.

7.4 Propane, Thermophysical Properties Data — R. D. Goodwin

Many of the available published physical properties data on propane

have been acquired via our Cryogenics Data Center from their

"Bibliography of References, Thermophysical Properties of Propane

in the Solid, Liquid and Gaseous Phases," April 27, 1976. We have

2
recently developed a vapor-pressure equation and formulations for

the orthobaric densities of propane based on this data.

8. Problem Areas . None.

9. Funding . January 1 - June 30, 1976.

Man-years expended

Equipment and/or Services Purchased

Total Reporting Period Cost

Balance Remaining

10. Future Plans.

Objectives and Schedule: Quarter 3 4

Measure, analyze and report

ultrasonic velocity data >

for ethane

.

Analyze available physical

properties data for propane.

Prepare and performance test

PVT apparatus for propane.

1.0

5 .2K$

71 .0K$

101. 3K$

3
1. Title . FLUID TRANSPORT PROPERTIES

Principal Investigator . Howard J. M. Hanley

2. Cost Center Number . 2750124

3. Sponsor Project Identification . NBS-Office of Standard Reference Data

4. Introduction . Methods for predicting the transport properties of fluid

mixtures are unreliable and data are scarce. Prediction methods are

needed, however, to supply the necessary design data needed to increase

efficiency and reduce costs.

5. Objectives or Goals . The long range or continuing goal of the program

is to perform a systematic study of the theories and experimental mea- surements relating to transport properties, specifically the viscosity

and thermal conductivity coefficients, of simple mixtures over a wide

range of experimental conditions. The specific objectives of the program include: 1) the systematic correlation of the transport properties

of simple binary mixtures and the development of prediction techniques,

2) development of a mixture theory for the dilute gas region and the

dense gas and liquid regions, 3) extension of the theory and prediction

techniques to multicomponent systems, and 4) suggested guidelines for

future areas of experimental work.

6. Background . A continuing program has successfully expanded the stateof-the-art of transport phenomena for pure fluids. Information for pure

fluids is required as a prerequisite for mixture studies. The theory

of transport phenomena has been developed and applied to produce practical

numerical tables of the viscosity, thermal conductivity and diffusion

coefficients of simple fluids: Ar, Kr, Xe, N2 , 02, F2 , He, H

2

, CH

4

. Recent work has extended this approach to ethane. It has been shown

that a successful mixture program can emerge from combining the results

for pure fluids with equation of state studies. The equation of state

work is being carried out by other investigators in this laboratory.

7. Program and Results . A procedure to predict the transport properties of

1 2 mixtures has been developed '

. The properties of nitrous oxide have

3 been studied and tabulated values are available .

8. Problem Areas . The lack of suitable mixture transport experimental data

for comparison purposes is the main problem.

9. Funding . January 1 - June 30, 1976.

10. Future Plans . The transport properties of ethane have been tabulated

and will be published. Propane is being investigated. A procedure to

calculate the transport properties of mixtures is in process of

publication. The procedure will be investigated further.

References

1. H. J. M. Hanley, Cryogenics (In press, 1976).

2. H. J. M. Hanley, AIChE J. (submitted)

.

3. H. J. M. Hanley, private report to be published. Data available from

the Cryogenics Division.

Allocation

Labor

Other Costs

60.0K$

0.4 MY

OSRD

24.2K$

1.8K$

Total 26.0K$

4
Title. PROPERTIES OF CRYOGENIC FLUIDS

Principal Investigators

.

G. C. Straty, B. J. Ackerson and D. E. Diller

Cost Center Number. 2750141

Sponsor Project Identification . NBS

Introduction . Accurate thermophysical properties data and predictive

calculation methods for cryogenic fluids are needed to support advanced

cryogenic technology projects. For example, liquefied natural gas is

expected to supply an increas ing percentage of the United States

energy requirements through 1990. Liquefaction plants, ships and

receiving terminals are being constructed to transport and store

natural gas in the liquid state (LNG) . Accurate thermophysical

properties data for LNG are needed to design low temperature

processes and equipment. Accurate data will benefit the energy

industries and the consumer by providing for safe and efficient

operations and reduced costs.

Objectives or Goals. The objectives of this project are to provide

comprehensive accurate thermodynamic, electromagnetic and transport

properties data and calculation methods for technically important

compressed and liquefied gases (helium, hydrogen, oxygen, nitrogen,

methane, ethane, etc.) at low temperatures. Precise compressibility,

calorimetric and other physical property measurements will be performed

to fill gaps and reconcile inconsistencies. Definitive interpolation

functions, computer programs and tables will be prepared for engineering

calculations. The immediate goals of this work are to obtain accurate

sound velocity and thermal diffusivity data for compressed and liquefied gases by using laser light scattering spectroscopy techniques.

Sound velocity data are useful for testing the consistency of

volumetric, calorimetric and thermodynamic properties data, and are potentially useful for density gauging applications. Thermal

diffusivity data are required for performing thermodynamic and heat

transfer calculations.

Background . When light is incident on a perfectly homogeneous fluid,

the reradiated (scattered) light field sums to zero in all but the

exact forward direction. For a "real" fluid, however, fluctuations,

arising through various mechanism, destroy the perfect homogeneity

and results in the scattering of light in other directions as well.

For example, thermally activated density fluctuations (phonons),

propagating with the characteristic velocity of sound, give rise to

scattered light Doppler shifted in frequency from the incident light

frequency and whose spectrum contains information on the sound

velocity and attenuation. Local non-propagating temperature fluctuations, which decay diffusively, give rise to scattered light in a narrow frequency band about the incident light frequency and whose

spectrum contains information on the lifetime of fluctuations (thermal

diffusivity). Since the frequency shifts are generally very small, it was not until the advent of the lasers with their extremely well defined

frequency, that practical experiments using these phenomena were possible.

The application of laser light scattering techniques to obtain thermophysical properties data was initiated to complement and check other

measurement methods and to solve measurement problems inherent in more

.conventional methods. For example, laser light scattering techniques

permit measurements of sound velocities for fluids under conditions

for which sound absorption is too large to perform ultrasonic
measurements; laser light scattering techniques permit measurements of

thermal dif f usivities under conditions for which convection interferes

with measurements of thermal conduction. The feasibility of light

scattering experiments to obtain data on binary diffusion coefficients

has also been demonstrated.

7 . Program and Results. Apparatus has been assembled for laser light

scattering spectroscopy on compressed and liquefied gases (76 - 300 K,

350 bars). The apparatus consists of a high pressure optical cell, a cryostat refrigerated by means of liquid nitrogen, an argon ion laser

and low-level light detection equipment.

The light scattered from fluctuations in the fluid can be analyzed with

either digital autocorrelation techniques for the examination of the

very narrow lines associated with scattering from temperature fluctuations (Rayleigh scattering) or with a pressure scanned Fabry Perot

interferometer for the measurement of the Doppler frequency shifts

associated with the scattering from propagating density (pressure)

fluctuations (Brillouin scattering)

.

Apparatus for photon-counting and digital autocorrelation has been

assembled, interfaced with computer facilities and programmed to enable

on-line data accumulation and analysis. Apparatus tests on well

characterized test fluids have been satisfactory. Measurements of the

thermal diffusivity of methane in the critical region are now in

progress. The obtained data appear to be consistent with scaled data

from other fluids. Extension of these measurements into regions more

removed from critical are planned.

8. Problem areas. Light scattered from pure fluids away from critical

is very weak. Initial attempts to obtain data in these regions

revealed the presence of an extraneous low-level signal previously

undetected. We have been unable to adequately treat this signal

mathematically and its presence appears to degrade data accuracy

excessively. We feel that this extraneous signal is a result of

building vibrations which modulate the light scattering signal. We

plan to isolate the complete optical system from the building using

an air suspension system in an attempt to remedy this problem.

Funding . January 1 - June 30, 1976

Man-years expended 0.3

Equipment and/or Services Purchased 4.7K$

Total Reporting Period Cost 17.5K$

Balance Remaining 0.0K$

10 Future Plans.

Objectives and Schedule: Quarter 3 4 Measure, analyze and report

thermal diffusivity

coefficient data for methane.

6
Title . PROPERTIES OF CRYOGENIC FLUID MIXTURES

Principal Investigators . M. J. Hiza, W. M. Haynes , A. J. Kidnay (parttime), and R. C. Miller (part-time).

Cost Center Numbers . 2750142, 2750145, 2750548, and 2574574

Sponsor Project Identification . NBS, NBS (OSRD) , NASA, AGA

Introduction

.

Accurate thermodynamic properties data and predictive

calculation methods for mixtures of cryogenic fluids are needed to

design and optimize low temperature processes and equipment. This

project provides new experimental measurements on equilibrium properties

and compilations of evaluated equilibrium properties data which are suitable for direct technological use or for the evaluation of predictive calculation methods

.

Objectives or Goals. The overall objectives of this project are to

provide critically evaluated data, original and from other sources, on

tne phase equilibria and thermodynamic properties of cryogenic fluid

mixtures. The program has been divided into the following elements:

a) Preparation of a comprehensive bibliography on experimental

measurements of equilibrium properties for mixtures of selected

molecular species of principal interest in cryogenic technology.

b) Selection and/or development of methods for correlation, evaluation

and prediction of equilibrium properties data.

c) Retrieval and evaluation of experimental data for specific mixture

systems selected on the basis of theoretical and/or technological

importance

.

d) Preparation of guidelines for future research based on the deficiencies noted in (a) , (b) , and (c) .

e) Performing experimental research to alleviate deficiencies and

provide a basis for improvement of prediction methods.

Background . A physical equilibria of mixtures research project was established in the Cryogenics Division in 1959. The initial effort,

based on a bibliographic search and other considerations, was directed

toward the acquisition of new experimental data on the solid-vapor and

liquid-vapor equilibria and physical adsorption properties for a limited

number of binary and ternary mixtures of components with widely separated

critical temperatures. Most of the systems studied included one of the

light hydrocarbon species -- methane, ethane, or ethylene (ethene) —

with one of the quantum gases -- helium, hydrogen, or neon. The data

for these systems led to significant improvements in the predictions of

physical adsorption equilibrium and a correlation for the prediction of

deviations from the geometric mean rule for combining characteristic

energy parameters. In addition, significant new information was obtained

for interaction third virial coefficients which was used in a correlation by one of our consultants, J. M. Prausnitz. The approach taken in

this work has been as fundamental as possible with the intention of

having an impact on a broad range of mixture problems.

Recent efforts have been directed toward problems associated with

systems containing components with overlapping liquid temperature ranges,

such as the nitrogen + methane system.
7. Program and Results . The recent progress is summarized as follows:

a) New liquid-vapor equilibrium composition measurements at selected

conditions for the methane + ethane and the methane + ethylene

systems have been obtained and analyzed. A paper reporting these

data has been released for publication and will be submitted to

the Journal of Chemical Thermodynamics

.

b) Work is continuing on the compilation and evaluation of liquidvapor equilibrium data, saturated liquid excess volumes, excess

Gibbs functions and Henry's constants for the methane + ethane

system. A paper discussing this work and the results is being

prepared for submission to the Journal of Physical and Chemical

Reference Data.

c) An equation of state, recently proposed by Peng and Robinson,

is being evaluated as a simple representation of the phase equilibria data over the entire liquid range for systems such as nitrogen

+ methane and methane + ethane. This equation appears promising in

the region where one component is supercritical, as well as the

region where both components are subcritical

.

Problem Areas. None

Funding . January 1 - June 30, 1976

Man-years expended

Equipment and/or Services Purchased

Total Reporting Period Cost

Balance Remaining

0.7

1.8K$

63.9K$

25 .0K$

10. Future Plans

Objectives and Schedule Quarter

Evaluate, correlate and report

liquid-vapor equilibrium

properties data for methaneethane mixtures.

Evaluate and report promising

calculation methods for LVE

and PVTx properties of methanenitrogen mixtures.

Prepare and performance test

PVTx apparatus for methanenitrogen mixtures.

Prepare and report graphs of

liquid-vapor equilibrium

properties data for methanenitrogen mixtures.

8
1. utie. DENSITIES OF LIQUEFIED NATURAL GAS MIXTURES

Principal Investigators . M. J. Hiza, W . M. Haynes, and R. D. McCarty

2. Cost Center Numbers . 2751574, 2752574

3. Sponsor Project Identification . LNG Density Project Steering Committee;

American Gas Association, Inc., Project BR-50-11.

4. Introduction

.

Accurate density measurements and calculation methods

for liquefied natural gas mixtures are needed to provide a basis for

custody transfer agreements and for mass, density, and heating value

gauging throughout the fuel gas industry.

The basis for the custody transfer of natural gas is its heating value.

It is difficult to determine and agree on the heating value of extremely

large volumes of natural gas in the liquid state . For example , methods

for calculating the heating value of a liquefied natural gas mixture

require knowing its density, which in turn depends on its composition,

temperature, and pressure. As the compositions of LNG mixtures vary

considerably, depending on the sources of the gas and the processing

conditions, accurate methods are needed for calculating liquid densities

at arbitrary compositions, temperatures and pressures. The accuracy is

important because of the extremely large volumes of liquid involved.

5. Objectives or Goals . The objectives of this work are to perform

accurate (0.1%) and precise (0.02%) measurements of the densities of

saturated liquid methane, ethane, propane, butanes, nitrogen and their

mixtures mainly in the temperature range 105-140 K, and to test and

optimize methods for calculating the densities of LNG mixtures at

arbitrary compositions and temperatures.

6. Background . This project is being carried out at NBS because of the

realization that equitable custody transfer agreements could be reached

more readily if the density measurements and the evaluation and development of calculation methods were performed by independent professionals

of established reputation.

An apparatus incorporating a magnetic suspension technique has been

developed for absolute density measurements on liquids and liquid

mixtures, particularly at saturation, for temperatures between 90 and

300 K. The estimated imprecision of measurement is less than 0.02%

and the estimated inaccuracy is less than 0.1%.

7. Program and Results . Saturated liquid density measurements have been

carried out for the following mixtures:

a) 0 . 30 CH. + 0

4 .70 C-.H_ (105 - 110 K)

-5 O b) 0 .86 CH. + 0 4 .14 C

3 H

g (105 - 130 K)

c) 0 .49 CH. + 0

4 .51 iC.H, n (110 - 125

10

K)

d) 0 . 59 CH, + 0 4 .41 nC .H-, (120 - 130

4 10 K)

e) 0 . 30 N

2 + 0. 70 CH. (100 - 120 K)

f) 0 .06 N

2 + 0. 94 C

2 H

g (105 - 120 K)

g) 0 .02 N

2 + 0. 98 C

3 H

g (110 - 115 K)

h) 0 .04 N

2 + 0. 96 C

3 Hg (105 - 110 K)
i) 0.07 N

2 + 0.93 C

3 Hg (100 - 105 K)

j) 0 . 34 N_ +0.34 CH

4 + 0 . 3 2 C

2 Hg (105 - 115 K)

k) 0.16 N

2 + 0.67 CH

4 + 0 . 1

7

C„H C (105 -

2 6 120 K)

1) 0 . 10 N

2 + 0.80 CH

4 + 0 . 1 U C

3 H

g (105 - 120 K)

m) 0.80 CH. + 0.10 C„H4 2 6 + U . 10 C

3 H

8 (105 - 120 K)

n) 0.05 N

2 + 0.85 CH4 + 0 .05 C

2 H

6 + nu . nU J^ C3 H

g (105 - 120 K)

o) 0.85 CH. + 0.05 C_H,

4 / 6 + 0 . 05 C 0 H 0 + 0. 05 iC

4 H (105 - 125 K)

P) 0.05

120 : N_ + 0.80 CH. +K)

4 0 .05 C

2 H

6 + 0.05 C H + 0.

J o 05 iC.

4 H

±i nu (105

q) 0.85 CH. + 0.05 C»H,

4 2 6 + 0. 05 C

3 H

8 + 0. 05 nC H4 1

U

(115 - 130 K)

r) 0.05

(1U j

N" + 0.79 CH. + inn v ^ 0 . 06 C

2 H6 + 0.05 C

3 Hg + 0. 05 nC

4 H 10

s) 0.85

(105

CH 4 + 0.05 C-H,

- 120 K)

2 6 + 0. 04 C3 H8 + 0. 03 iC

4 H

1Q

+ 0.03 nC

4 H

10

t) 0.04 N 2 + 0.81 CH 4 + 0.05 C 2 H + 0.05 C H + 0.025 iC H

+ 0.025 nC

4 H1Q (105 - 120 K)

This completes the planned density measurements for binary and multicomponent mixtures. All of the density data are now being used to

evaluate and optimize several calculation methods for predicting the

densities of multicomponent LNG type mixtures.

A manuscript which discusses the magnetic densimeter and method of

measurement in detail has been submitted to the Review of Scientific

Instruments for publication. Included is an analysis of the measurement

errors and data for pure nitrogen and methane.

8 . Problem Areas . None

9. Funding . January 1 - June 30, 1976

2751574 (measurements)

Man-years expended 0.8

Equipment and/or Services Purchased 1.6K$

Total Reporting Period Cost 53.1K$

Balance Remaining 22.7K$

2752574 (calculation methods)

Man-years expended 0.25

Equipment and/or Services Purchased 3.9K$

Total Reporting Period Cost 20.6K$

Balance Remaining 4.0K$

10
1 0 . Future Plans

.

Ic;ec~ives and Schedule: Quarter

Analyze and report orthobaric

liquid density measurements

for binary and multicomponent

fixtures :: IXG ::r::re:.:: , evaluate, optir.ize ar. recor

several calculation methods

for orthobaric liquid densities of LNG type mixtures

.

:
Title . LOW TEMPERATURE MATERIAL BEHAVIOR

Principal Investigators . H. I. McHenry and R. P. Reed

Cost Center Number . 2750430

Sponsor Project Identification . Maritime Administration Misc. P.O.

#400-58074.

Introduction . For cryogenic applications, the ASME Boiler and Pressure

Vessel Code and the API Standard 620 Appendix Q Code specify the same design allowable stress level for 5Ni steel as for 9Ni steel. Since

5Ni steel costs approximately 20% less than 9Ni steel, significant cost

savings could be achieved by using this material for LNG applications.

At the present time, 5Ni steel cannot be used in place of 9Ni steel for

marine applications because the U. S. Coast Guard has not approved it.

The principal reasons that the USCG has delayed approval are lack of

service experience in land based tankage and concern that the fracture

resistance of the weld heat affected-zone (HAZ) is inadequate.

Objectives . This program is being conducted to evaluate the fracture

resistance of the heat affected zone of 5Ni steel weldments at room

temperature, 111 K and 76 K. Background . This program is a continuation of the program conducted by

Reed, et al. to determine the mechanical properties of candidate materials for LNG tankage. The work demonstrated that 5Ni steel plate has

adequate mechanical properties for LNG applications. Further work was recommended to verify that the plate properties would be retained in the

weld heat affected zone. Program and Results . The program to evaluate the fracture behavior of

the heat-affected zone in 5% Ni steel weldments has been completed.

The fracture properties of the base metal and the heat affected zone

(HAZ) of 5% steel weldments were determined at room temperature, 111 K

and 76 K; emphasis was placed on tests at 111 K, the minimum boiling

point of liquefied natural gas (LNG). The 32 mm- thick test plates, which

met the requirements of ASTM A645, were welded using the pulsed-powergas-metal-arc process at a heat input of 10.6 kJ/cm. The fatigue crack

growth rates were determined for cracks growing through the thickness

using four-point bend specimens. At 111 K, the rates in the base metal

were essentially the same as found by other investigators; however, the

rates in the HAZ were up to 10 times faster than previously reported.

Fracture toughness tests were conducted under load-controlled conditions

using J-integral procedures. At 111 K, the base metal and HAZ toughness

values were 30 and 50 percent lower, respectively, than toughness values

obtained previously for the same plate of test material under displacementcontrolled conditions. Fracture mechanics analyses using the results

reported herein indicate that 5% Ni steel is suitable for LNG applications, but more conservative estimates of fatigue life and critical crack

size are necessary.

A complete report of this investigation is presented in a paper entitled

"Fracture Behavior of the Heat Affected Zone in 5% Ni Steel Weldments."

(See Appendix A.)

Problem Areas . None. The program has been completed.

12
9. Funding . January 1 to June 30, 1976

Expended $2 OK

Remaining OK

10. Future Plans. None. The program has been completed.

\A

i

13
1. Title . PROGRAM FOR REDUCING THE COST OF LNG SHIP HULL CONSTRUCTION -- PHASE II SHIP STEEL IMPROVEMENT PROGRAM

Principal Investigators . H. I. McHenry, M. B. Kasen, and R. P. Reed

2 . Cost Center Number . 2753430 - LNG Ship Hull Materials (Shipyard Contracts)

2751430 - LNG Ship Construction Materials (Metallurgical Evaluation)

2752430 - LNG Ship Hull Materials (Fracture Properties)

3. Sponsor Project Identification . Maritime Administration Misc. P. 0.

400-58073.

4. Introduction . Construction of LNG tankers requires the use of fine

grain normalized steels for the part of the hull structure that is

cooled by the cargo to temperatures in the range of 0 to -50°F. Several

ABS steels have satisfactory base plate properties but extreme care must

be exercised during welding to avoid degradation of the steel adjacent

to weld (the heat affected zone) to a level of toughness below U. S.

Coast Guard requirements. Significant cost problems are being encountered by U. S. shipyards due to the resulting inefficient low-heat- input

welding procedures that must be employed to meet the fracture requirements in the heat affected zone. The feasibility of reducing the cost of LNG ship hull construction was investigated in Phase I of this project, leading to the Phase II program described below.

5. Objective . The objectives of the Phase II program are 1) to have the

four major plate producers supply three LNG shipyards with production

heats of ABS steels modified to possess improved transverse fracture

properties at low temperatures, 2) to have the LNG shipyards evaluate

these plates by qualifying optimum welding procedures in accordance with

the USCG requirements, and 3) to provide a metallurgical evluation of

factors that influence heat affected zone toughness in the improved

steels

.

6. Background . Early in 1974, the Welding Panel of MarAd ' s Ship Production

Committee recommended that a program be conducted to reduce the cost of

ship hull construction. NBS was requested by MarAd to propose such a program to the LNG subcommittee of the Welding Panel at a meeting in

Boulder in August. In mid-October, MarAd approved the initial phase of

NBS 1 s recommended program, I.E., to survey the problem and the technology available for its solution. On the basis of this survey and as the result of a meeting of the Welding Panel in March, 1975, a coordinated program involving the LNG shipyards, the steel suppliers, and NBS

was recommended to MarAd and to the Welding Panel. This program was

approved and work started in May 1975.

7. Program and Results . Steel deliveries to the three LNG shipyards started

in April 1976 and will be complete by August 1976. The status of the

steel shipments is summarized as follows:

14
Shipyard

Avondale

General

Dynamics

Newport News

Steel Co.

Armco

U.S. Steel

Bethlehem

Bethlehem

Bethlehem

Steel Grade

V-062

V-062 (SSC)

CS (SSC)

ASTM A537A-Mod

ASTM A5 37A-Mod

V-051 (SSC)

Delivery Date

August 1976

August 1976

June 1976

April 1976

August 1976

June 1976

* The steel grades V-062, V-051 and CS are American Bureau of Shipping

grades

.

** SSC. Sulfide Shape Control employed.

The first heat of ASTM-A5 37-Mod steel delivered to General Dynamics did

not meet the specified properties due to inadequate sulfide shape

control. This heat was eliminated from the program and a second heat was ordered for replacement. Shipments to Avondale were delayed because of

difficulties in disposing of the balance of the two test heats not

needed for experimental purposes. The disposition problem was resolved

by Armco who sold the balance of the heat for use in construction of an offshore drilling rig.

The properties of the steel delivered to date have been outstanding

(ASTM A537A-Mod excepted)

Steel Grade

V-051

CS

Steel Co,

Bethlehem

U.S. Steel

Plate

1/2 in. thick

1 in. thick

(PC #1)

1 in. thick

(PC #2)

1 in. thick

1/2 in. thick

Transverse Charpy Energy

(ft lb)

240 ft lb avg @ -60°F

77 ft lb avg @ -60°F

120 ft lb avg @ -60°F

174 ft lb @ -40°F

124 ft lb @ -40°F

Each of the shipyards plans to start the weld evaluation test program

during the next reporting period.

8. Problem Areas . The development work has been delayed because of

problems in finalizing the steel orders.

9. Funding . January 1 - June 30, 1976.

Cost Center Cost to June 30, 1976

2753430 109K$

2751430 57K$*

2752430 42K$

* Includes Phase I costs.

Balance

36K$

23K$

18K$

10. Future Plans . Lukens Steel Company has been asked to submit a proposal

for evaluating two heats of higher-strength ship steel meeting the

requirements of V-062 with a minimum yield strength of 51 ksi.

15
1. Title . CUSTODY TRANSFER - LNG SHIPS

Principal Investigators . R. S. Collier, P. J. Giarratano, and J. D.

Siegwarth

2. Cost Center Number . 2750460

3. Sponsor Project Identification . Maritime Administration, Misc. P.O.

#400-58074, #400-69012.

4. Introduction . In response to a request from the U.S. shipbuilding

industry, NBS is conducting an independent design review of the shipboard custody transfer systems under the sponsorship of the Maritime

Administration and in cooperation with the major U.S. shipbuilding

companies

.

5. Ob j ectives . The objectives of this program are to 1) Identify the

major technical areas relating to uncertainties in the measurement of

total mass and total heating value, 2) Estimate uncertainties in the

total mass and total heating value due to these identified factors,

3) Develop a proposed testing program for custody transfer system components, and 4) Investigate improved gauging techniques.

6. Background . Calendar year 1974 funding provided for the initial re- view of ships designated by MA Design LG8-S-102a MA Hulls 289, 290, 291.

The current funding provides for an extension of this program to include

ships of other designs which are being built by the major U.S. shipbuilding companies and also to verify tank survey and gauging methods

for LNG custody transfer.

7. Program and Results . A. Working relationships with four major U. S.

shipbuilders have been initiated. Most of the problem areas which

are common to custody transfer systems of all types have been identified

and are listed as follows:

1. Density

a) accuracy

b) rangeability

c) stability

2. Tank Strapping (Tank Surveys)

a) thermal effects

b) loading factors

c) measurement techniques

3. Convection (Non-Uniform Density)

a) density or composition stratification

b) possible isolation of measurement stillwells

4. Tank Weathering

a) time changes in composition, stratification, etc.

b) composition measurement

c) sampling

5. Liquid Level/Total Volume Measurement

6. Pressure and Temperature Measurements (gradients included).

7. Electronic Signal Conditioning, Data Reduction, Analysis and

Readout

B. First Quarter - Three different methods for modeling the LNG tank

weathering problem were developed. All of these methods assumed an equilibrium or quasi-equilibrium situation within the tank. An actual

16
experimental condition is the only method of testing the validity of

this assumption; this should be done in the latter stages of the investigation. For the present, all three models will require extensive com- puter analysis in order to obtain useful predictions and will also rely

on an adequate correlation technique for the mixture phase equilibria.

This study should be undertaken as soon as there is sufficient confidence

in the validity of the correlation technique.

The draft submitted in the last report relating the density, dielectric

constant and temperature for LNG mixtures was reviewed by the editorial

board and submitted for publication.

Second Quarter - NBS became involved in the tank survey procedures for

obtaining the tank capacity tables for the LNG ships designated in paragraph 6 above. The task for NBS is to estimate the uncertainty in the

tank volume which is obtained by a photogrammetric process using multiple

station analytical stereotriangulation . The task is divided into three

parts. First, the uncertainty in obtaining the coordinates of targets

painted on the inside surface of the tank. Second, the uncertainty of

numerical integration of the volume using a specified number of target

locations; and third, the changes in tank shape due to stress loading

and thermal contraction factors.

Design and construction has been started for gauge blocks and rods to

be used for verification of coordinate measurements. Also, numerical

integration techniques based on spherical harmonics have been obtained

for converting the target locations into a volume measurement. Another

program based on a least squares technique is in progress. Collaboration

with the ship owners and builders is in progress in order to obtain

nominal surveys as constraints on the numerical techniques and also to

schedule the NBS procedures into the construction schedule for the tanks.

Further work is in progress using the RF gauging technique. A large gas

holder, 16 ft in diameter and 18 ft high with a center tube (or tower)

has been resonated successfully. Further experiments on a 30 ft diameter

sphere are scheduled for late summer. A portable instrumentation package has been designed and constructed and is presently in use. One

phase of calculation for RF gauging has been completed for a liquid-gas

fill condition.

Problem Areas. None.

Funding . January 1 - June 30, 1976.

Man-years expended 0.8

Total Cost 47.0K$

Balance Remaining 40.7K$

Future Plans . 1. NBS will install gage blocks and gage rods (which are manufactured,

targeted, and calibrated at NBS) as one independent check on the accu- racy of the photogrammetric coordinate determination.

2. NBS may require 100 additional targets (one per plate). It is clear

that four targets per plate is sufficient to determine the tank shape

factors (assuming a constant radius of curvature for each plate) but it

is also clear that extra (redundant) data is necessary to determine the

uncertainties in the shape factors. It is not clear that adding 100

extra target points is the best way to obtain the redundant data; measuring the uncertainty in the radius of curvature of a number of plates

in place could be another method.

17
3. Other nominal (spot check) surveys of the inside of the tank will

be necessary to provide a first order (mathematical) constraint on the

calculation of the tank shape. It has not been decided whether NBS

will perform that survey or obtain information from other surveys at the

tank site.

4. A system of target identification will be established and that NBS

will be apprised of that system at the earliest possible date.

5. NBS will obtain the target coordinate data in a form suitable for

independent calculations (data cards)

.

6. NBS will obtain certain detailed information from the subcontractor

for the ship builder concerning the determination of target coordinates

from plate coordinates and also in determining tank shape factors from

target coordinate data. Also held by the subcontractor for the shipbuilder are some technical publications and their updates which are being

requested by NBS.

7. The shipbuilders will supply currently available calculations or technical papers, if any, relating to the calculation of stresses in the

tank and the stress-strain relationships caused by tank loading. Outputs

from strain gages will also be useful.

8. NBS will also obtain further information concerning the tank thermal

contraction coefficients both at and around ambient temperatures and

also down to LNG temperatures.

9. We will perform further calculations concerned with LNG tank weathering.

10. We will also perform an RF gauging experiment in a 30 ft. diameter

spherical LNG tank.

L8
i. Title . HEATING VALUE OF FLOWING LNG

Principal Investigators . J. A. Brennan and J. M. Arvidson

2. Cost Center Number . 2756579

3. Sponsor Project Identification . Pipeline Research Committee (American

Gas Association) PR-50-48.

4. Introduction . This project will test instrumentation for making heating

value measurements in actual applications of flowing LNG. Information

from projects currently underway by Younglove (cost center 2757574) on densimeters and by Haynes and Hiza (cost center 2751574) on mixture

densities will be utilized where appropriate to provide state of the

art information.

5. Ob j ectives . The objective of this program is to measure total heating

value of LNG flowing in a pipeline by the integration of individual

measurements of flow, density and specific heating value. Flow measurement requires determination of flowmeter performance in line sizes

larger than presently available calibration facilities. Therefore, a secondary objective is to establish appropriate flowmeter scaling laws.

6. Background . The LNG flow facility at NBS will be utilized to evaluate

the response of the individual elements in the heating value measurement. Different compositions of LNG will be prepared to provide a range

of densities and temperatures sufficient to determine any dependencies.

A limited amount of sampling work is included to determine the relative

importance of this parameter to the overall measurement.

Flowmeter scaling is being done utilizing the cryogenic and the water

flow facilities at NBS and private LNG peak shaving facilities. This

portion of the program is behind schedule because of scheduling problems at the private LNG facilities.

7. Results . A. Three tests of the eight inch flowmeter at the Transco

peak shaving plant were completed during this reporting period. The

results of those tests and the results from the four inch flowmeter

test referred to in the last report are shown in figure 1. As can be seen in this figure, there is a disturbing difference between the data

taken during the last test and almost all the previous tests. Although

the difference was almost within the experimental error tolerance, the

internal consistency strongly suggests something was performing differently during the last test. At the last meeting of the Supervisory

Committee several courses of action were suggested to identify the sources of the discrepancy.

One area of concern was the stability of the orifice flowmeter recording

instrumentation. This does not appear to be a problem since the recorders were calibrated by Transco measurement personnel between each of the

LNG tests. No adjustments were required during any of these calibrations

It was also suggested that new instrumentation be installed to record

the orifice flowmeter data on our data logger. This suggestion was accepted and it was agreed that this additional information could be

recorded within the existing project funding. This can be done by re- ducing the amount of testing on the NBS LNG flow facility.

There is a severe problem of data transmission at the Transco site. The

environment is extremely noisy and requires high quality instrumentation

if any improvement is to be gained over the existing system. Since

there is no available wiring or empty conduits running between the two

measurement points (liquid and gas), it is recommended that the data be

recorded on separate units. The units can be electrically tied together

so that the recordings are synchronized. Using this procedure will re- sult in less interference and less expensive data transmission lines.

19
To provide new instrumentation and recording equipment will cost between $7000 and $9000. This will provide instrumentation necessary to

record the output from two orifice runs. The actual cost will depend

on the choice of pressure transducers and recording system. The recom- mended pressure transducers would cost $3250 and the recommended recording system would be cost shared on an equal basis with another project

resulting in an expense of $3450. This recording system would utilize

a tape recorder already available at NBS. Approximately $1000 would be

needed to install and check out the system for a total estimated expense

of $7700.

The cost sharing of the recording system can be accomplished provided

NBS is permitted to retain title to the equipment. If this is not

possible then the most cost effective procedure is to fabricate a system

similar to the one now being used at Transco. This latter arrangement

would also utilize the available tape recorder but would cost the project

approximately $4700 resulting in a net cost of almost $9000. Both

estimates can be reduced by $600 if lower cost pressure transducers are selected

.

At the last meeting it was also recommended that the data from Transco 's ultrasonic flowmeter be recorded on the existing data logger. The vortex

shedding flowmeter has redundant sensing available and this output will

also be recorded in the future. The logger has been returned to Boulder

and the necessary modifications are being made to record these two additional bits of information.

B. Liquid Nitrogen Tests

a) Flowmeter

The four inch flowmeter tested at Transco was returned to NBS and retested

on the nitrogen flow facility. Unlike the first tests, the recent test

included the eight by four inch reducers on the flowmeter piping just as

it was tested at Transco. The average meter factors measured during

these two tests differed by only 0.12 percent. Therefore, there doesn't

appear to be any reason to question the stability or the installation of

the four inch flowmeter during the LNG tests at Transco.

Tests on the four inch flowmeter were also run using one of the electronic

signal conditioners supplied with the eight inch flowmeter presently installed at Transco. This particular signal conditioner had failed during the LNG test last January 18th and had been repaired by the manufacturer. The results obtained from this test indicated a very sensitive

dependence on sensor current and might be the cause of the shift in the

last LNG test at Transco. The system was set up and adjusted on January 19th by the manufacturer but it is possible that it was slightly out

of adjustment during the tests on February 2nd and 3rd. If this problem

did, in fact, exist it could explain the change in bias observed during

the February tests. It might be possible to check this problem during

the next LNG test but due to the nature of the problem the check can't

be conclusive.

Additional information on meter factor shifts from water to liquid nitrogen on another two inch flowmeter was also recently obtained. The ratio

of the liquid nitrogen meter factor to the water meter factor was 1.0206.

On the previous two inch meter the ratio was 1.0156 and on the four inch

it was 1.0165. There is almost 0.5 percent difference in the ratio for

the two 2-inch flowmeters. Without additional information on other meters

there is no way to tell whether the difference is typical or not. The

difference is larger than desirable and points out a need for additional

information on other meters.

20
In addition to the information on water to liquid nitrogen meter factor

shift, information on water calibrations at NBS Gaithersburg and a private

calibration facility was also obtained. There was remarkable agreement

between the two facilities. This information is very useful and en- couraging since the private facility has a larger capacity than the NBS

facility and could be useful to this project in the future.

C. Densitometer

Liquid nitrogen calibration of the densitometer used during the last LNG

test at NBS was started and is continuing. This densitometer is a re- placement for the one that failed and has had no previous application in

cryogenic service. During the first liquid nitrogen test there was an apparent shift in the performance and, according to the manufacturer,

shifts can occur in the densitometer performance during the first few

cycles to cryogenic temperature.

Additional data is being taken on the densitometer each time the flow

facility is operated. This additional data will be used to check the

stability of the densitometer for as long as possible before moving it

back to the LNG facility.

Problem Areas . None

Funding . January 1 - June 30, 1976.

Man-years Expended 0.9

Total Reporting Period Costs 58.0K$

Balance Remaining 66.0K$

Future Plans . Instrumentation is being prepared for both the future tests

at Transco and the NBS LNG facility. Component integration testing of

the LNG heating value measurement station will be started in the fall.

An existing minicomputer will be used in this work. No major problems

are anticipated in completing this phase of the program.

21
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22
Title . LNG DENSITY REFERENCE SYSTEM

Principal I nvestigators . Ben Younglove and John Arvidson

Cost Center Number . 2757574, 2750161

Sponsor Project Identification . American Gas Association, Inc.,

Project BR-50-10, National Bureau of Standards

Introduction . A density reference system has been developed to evaluate

the ability of commercially available instruments to measure densities

of LNG directly. Density is an essential measurement in determining the

total energy content of natural gas reservoirs. This effort is oriented

towards metrology, whereas the output from cost center 2751574 will provide basic reference data on pure liquids and mixtures, to evaluate

methods for calculating the density indirectly.

Objectives . The objective of this research is to provide a system for

evaluating the density measurement capability of commercially available

meters. From the commercial meters we will attempt to select one or two capable of performance as transfer standards, in order to provide

traceability of accuracy to field density measurement systems.

Background . The density reference system project was initiated in 1973.

Since that time the reference system has been designed, constructed, and

is now in operation, evaluating commercial density metering systems.

Program and Results . Data have been accumulated on performance of the

vibrating cylinder, vibrating plate, and the capacitance meter in liquid

methane, methane + ethane, methane + propane, methane + butane, methane

+ nitrogen, and also in multicomponent LNG type mixtures.

A draft of a summary report of the results obtained for these meters has

been submitted to the sponsor for review; data for the individual meters

has been submitted to the respective manufacturers for review. A

provisional accuracy statement for the density reference system is also

under review. Additional data are being taken on pure methane to

increase the confidence of the accuracy statement and to determine a more precise value for the random error associated with the measurement

of the apparent weight of the silicon plummet immersed in LNG.

Problem Areas . Review of the data shows a small but perceptible drift

in the vibrating cylinder data; a zero offset has been found in the

Archimedes principle densimeter data, probably due to uncertainties in

fluids properties data for methane and nitrogen; an electronic readout

parameter change is needed for the capacitance densitometer, particularly

in the presence of nitrogen; and a mechanical stability offset occurs periodically with the vibrating plate densimeter.

Also under investigation are small but perceptible shifts in the mea- surements obtained from the density reference system on each occasion

of fluid fill. There is also a problem in determining the composition

of the fluid for multicomponent mixtures containing nitrogen (butanes

also may give a similar problem) due to lack of accurate liquid-vapor

equilibrium data for LNG type mixtures.

Funding . January 1 - June 30, 1976

Man-years Expended 0.5

Total Project Cost 32.0K$

Balance Remaining 0.0K$

Future Plans . Review and revision of the provisional accuracy statement

will be completed during the next reporting period.
1. Title . LNG SAMPLING MEASUREMENT STUDY

Principal Investigator . W. R. Parrish

2. Cost Center Number . 2750575

3. Sponsor Project Identification . LNG-Sampling Measurements Supervisory

Committee

.

4. Introduction . Composition is used to determine both the heating value

and the quantity (through density) of LNG shipments. Thus, any error

in composition doubles when calculating the total heating value and

dollar value of a LNG tanker cargo. Compositions are determined by

sampling LNG, on either a batch or continuous basis, and analyzing the

vaporized mixture. Although several sampling techniques exist, none

have received widespread acceptance in the LNG industry. Also, a standard technique has not been established for analyzing the vaporized

sampled

5. Objectives or Goals . The objectives of this work are to evaluate existing sampling techniques appropriate to LNG systems and to recommend the

most accurate analytical technique. Only sampling devices applicable

to pipelines are being considered. The sampling techniques are judged

on:

a) representativeness of sample,

b) insensitivity of results to composition, temperature, pressure,

degree of liquid subcooling, flow rate and operator, and

c) simplicity.

Initial evaluations will be made in a laboratory-scale apparatus; final

evaluation of the most promising sampling techniques will be performed

in the LNG flow facility.

6. Background . This work is being performed at NBS because there is a need

to determine the best means for obtaining the composition of LNG shipments. Current LNG buying contracts include specifications on when and

how many liquid samples are to be taken but omit the sampling technique

to be used. The evaluation of sampling techniques by impartial professionals will lead to the acceptance of the most accurate composition

determination method by all parties involved in LNG custody transfer.

7. Program and Results . This program has just started and the laboratory

apparatus is in the design and building stage. Evaluation of analytical

techniques is just underway.

8. Problem Areas . None.

9. Funding . January 1 - June 30, 1976.

Man-years expended 0.2

Total reporting period cost 12.0K$

Balance remaining 13.0K$

10. Future Plans

Objectives and Schedule: Quarter 3 4 Evaluate analytical techniques

Evaluate sampling techniques in

Scale apparatus

* laboratory

24
SURVEY OF CURRENT LITERATURE Oil LNG AND METHAIJE

rr:n::;al -r.ves^igatcr . Neil A. Olier.

Cost Center Number. 2759574

:c::.;:r -reject -dertif . .-.-.ericar. I-as Association, Inc.,

4. Ir.~rccuct.icr. . It is important that all NBS personnel working in LNG, as well as the AGA and others, keep up with what is going on throughout the

world in the LNG field. This project is designed to provide the Current

Awareness and other information services to allow workers to keep

abreast of new research and other developments

.

5. Infectives cr Seals . We will publish and distribute each April, July,

Cctccer, arc January a listing of all significant papers, reports, and

patents relating to methane and LNG properties and technology. The

references will be listed under convenient subject headings. The

Quarterly will be distributed to all interested AGA member companies and

be made available to the general public on a subscription basis. In

addition, LNG related information will be entered into the Cryogenic

Data Center's Information System for quick retrieval. A continuing

awareness of the current publication scene will be maintained for any

new periodical to be reviewed cover-to-cover. Finally we will update

and make available comprehensive bibliographies on the properties and

technology of LNG. There are three bibliographies involved: methane

properties, methane mixtures properties, and processes and equipment

involving methane and LNG. These three will be updated each October.

6. Background . In 1965 we made a thcrcugh review cf the world's publications to determine which periodicals and abstracting services should be

scanned cover-to-cover to adequately encompass the LNG field. The

result is that we now scan over 300 primary publications and nearly 30

secondary publications. Of these, approximately one-third are directly

related to LNG. In addition, within the past two years we have increased

our coverage of the energy field to include hydrogen as a future fuel.

Much of this information is also pertinent to LNG and as such is listed

in our LNG-related publications. Our Current Awareness Service has

been published weekly since 1964 (beginning in 1975 the publication

became biweekly) and the Liquefied Natural Gas Survey has been published

quarterly since 1970.

7. Program and Results . Four issues of the LNG Quarterly are prepared each

year and distributed. There are now 121 subscriptions going to AGA

Member Companies and 155 to other subscribers.

The three comprehensive bibliographies mentioned in section 5 have been

reviewed and shortened, and more selective bibliographies have resulted.

The latest versions were completed as of January 1, 1976.

B-1371 THE THERMOPHYSICAL PROPERTIES OF METHANE AND DEUTERO-METHANE

IN THE SOLID, LIQUID AND GASEOUS PHASES - A SELECTED BIBLIOGRAPHY. Indexed by property, phase and author, 80 pages

(Jan 1976) . ($8.00)

.

B-1372 THE THERMOPHYSICAL PROPERTIES OF METHANE MIXTURES - A

SELECTED BIBLIOGRAPHY. Indexed by property, system and

author, 140 pages (Jan 1976). ($10.00).

H - 1 2 € 4 PROCESSES AND EQUIPMENT INVOLVING LIQUEFIED NATURAL GAS AND

METHANE - A SELECTED BIBLIOGRAPHY. Indexed by subject and

author, 76 pages (Feb 1975). ($8.00).

25
B-1367 Supplement to B-1264, indexed by subject and author, 40 pages

(Jan 1976) . ($5.00).

Over the past five years we have distributed over 420 copies of these

and the comprehensive bibliographies. A bibliography on LNG Patents

was supplied to AGA in May, 1975. Two supplements to this were also

completed, one in July 1975 and one in January 1976.

8. Problem Areas . None.

9. Funding . January 1 - June 30, 1976.

10. Future Plans . Issue 76-2 was delivered. to the printer on July 2, 1976.

For the past six months all printing, distribution and subscription

fulfillment functions have been handled locally by the NBS-Cryogenic

Data Center. This has solved the problems we previously had when dealing

with the National Technical Information Service. We feel we can now provide a responsive and responsible service to our customers in the

natural gas industry.

Labor

Other Costs

Total

4.6K$

0. 9K$

5. 5K$

Remaining 0. 6K$

26
Txtie . LIQUEFIED NATURAL GAS TECHNOLOGY TRANSFER

Principal Investigator . D. B. Mann

Cost Centers . 2750403, 2751403, 2752403, 2750570, 2754574 and 2758574.

Sponsor Project Identification . Maritime Administration Miscellaneous

Purchase Order No. 400-69012; American Gas Association, Inc. Project

BR 50-10; American Bureau of Shipping letter dated 21 November 1975.

Introduction . The liquefied natural gas program at the Cryogenics

Division of NBS-IBS/Boulder represents an investment by industry and

Government agencies of over $5 million over the past six years. This

investment was designed to develop reference quality properties data for

both fluids and materials, instrumentation and measurement technology

for the use of the LNG and related industries. Information developed

under this program must be transmitted to the ultimate user in a timely

and useful format. The classical publication methods of NBS most

certainly provide the scientist and research engineer information in a form most useful to the academic or near academic community. However,

as a result of extensive assessments of user requirements, it was found

that an additional effective mode for technology transfer would be an LNG Materials and Fluids Data Book. A complete outline and planned table

of contents has appeared in previous semi-annual reports. The Maritime

Administration of the Department of Commerce and the American Bureau of

Shipping have agreed to sponsor the first year's efforts on the materials

section and the American Gas Association, Inc. has agreed to sponsor the

section on fluids and fluid mixtures. The project was begun on April 1,

1976.

Ob j ectives . The Liquefied Natural Gas Materials and Fluids Data Book

will provide a method of quick dissemination of property data and related

information for the effective generation, utilization and transportation

of LNG. The object is to improve technology transfer from the current

NBS Cryogenics Division LNG physical measurements program to the users,

including federal agencies, the states and industry. For the purpose of

this data book, liquefied natural gas is defined as a cryogenic mixture

(at less than approximately 150 K) of hydrocarbons, predominantly methane,

with less than a total of 20% of the minor components ethane, propane,

iso and normal butane, and nitrogen as an inert contaminant. LNG materials

will be those associated with the liquefaction, transport and storage of

liquefied natural gas.

Background . The Data Book is only one of a number of information dissemination methods used to provide workers in the liquefied natural gas

(LNG) industry with properties data of known quality in a format consistent with the requirements of the intended user. In the case of the

LNG Data Book, the intended audience is the field engineer, plant

manager, ship designer or process engineer interested in a ready reference

of assessed quality for data to be used in conceptual design, process

monitoring, process analysis, and intercomparisons where precision and

accuracy are secondary to specific problem solutions. The hierarchy of

accuracy and precision will be defined and traceable through reference

to scientific and engineering literature.

Data is classified into three groups by the NBS Cryogenics Division.

Group 1 . Data which has been generated experimentally by NBS or has been

assessed, evaluated or experimentally verified by NBS.

Group 2 . Data which has been assessed and evaluated by NBS.

27
Group 3 . Data available in the scientific engineering literature

through the NBS Cryogenic Data Center or elsewhere. No NBS evaluation

or assessment has been made at this date.

In general, all data included in the LNG Data Book will be from groups 1 and 2. No new assessments or correlations are anticipated or required

for this work.

Data will be presented primarily in graphical form. Tables and analytical

expressions will be used only where absolutely necessary. Graphs and

charts will be in loose-leaf form for ease of updating and additions.

This form will also allow immediate implementation for data already

available under the NBS LNG program and will provide a convenient form

for the output of data from existing projects. The data book will not

be a substitute for traditional publications in the scientific literature

where measurement science, technique, precision and accuracy are paramount,

but will provide the data and references for the necessary assessment by

the user.

7. Program and Results . This publication is designed primarily for user requirements and, therefore, we have requested and received special con- sideration from NBS in its publication. The publication of both graphical

and tabular data will be in a dual system of units. These units will be

the traditional LNG industry British system of Btu, pound, degree

Fahrenheit and the SI system of joule, kilogram and degree Kelvin. It is

the intent to give the equal weight to each system of units. For instance,

in a graphical format with dual scales the test will be to recover

graphical information in either set of units with equivalent precision.

A three-post expandable post binder has been selected and special graphics

have been generated and submitted to sponsors for approval. Section

tabbing and graph formats have been fixed for both materials and fluids.

Nine structural metals have been selected with additions possible upon

consultation with sponsors. Primary emphasis in the fluids section will

be on pure methane, pure nitrogen, and methane-nitrogen mixtures. Over

20% of the material to be put in graphical form as been completed to

date

.

8. Problem Areas . None.

9. Funding . The program was funded April 1st at 130K$ for a 12-month period.

Labor (Man-years) 0.2 5 Total to 30 June 1976. 23.4K$

10. Future Plans . Binder and divider tabs will be put on order in August

with the printing of groups of graphs to proceed periodically thereafter.

It is planned to begin distribution the first quarter of 1977.

28
i. Title . OIML JOINT SECRETARIAT ON LNG MEASUREMENTS

Principal Investigator . Douglas Mann

2. Cost Center Number . 2750104

3. Sponsor Project Identification . American Gas Association, Inc.,

NBS-Office of International Standards; and NBS-Cryogenics Division.

4. Introduction . The liquefied natural gas program of the National Bureau

of Standards Cryogenics Division has, over the past five years, provided

the gas industry and interested Government agencies with properties data

on materials and fluids, instrumentation, and measurement assistance in

the support of commerce in this significant and growing segment of the

supplementary fossil energy supply. Support of this program by the

American Gas Association, Inc. and Federal Government agencies such as the Maritime Administration (MarAd) , NASA, GSA, Federal Power Commission

and the NBS-Office of Standard Reference Data has provided a basis for

the national acceptance of the results of the NBS LNG program. Through

the U.S. membership in the International Organization of Legal Metrology

there exists, at the present time, an opportunity to extend, internationally, the utility of data and measurement practice developed under

our joint Government/industry program. We have been requested (by OIML

membership) to establish an LNG Measurement Secretariat within OIML which,

if implemented, would provide a significant international forum for the

results of our joint work. It is believed that a joint Secretariat with

the LNG industry would provide the most effective means of accomplishing

these objectives.

5. Objectives or Goals . Our objective is to accomplish the following goals

within the next three years.

a) To establish U.S. (NBS) thermophysical properties data for LNG as the standard data in international usage.

b) To establish U.S. (NBS) materials property data used in fabrication

and construction of LNG facilities (liquefiers, storage, transport) as the standard data in international usage.

c) To establish U.S. (NBS) approved measurement technology and

instrumentation as related to LNG (pressure, temperature, density, liquid

level, flow) as the standard in international LNG trade. The precedent

has been established with the successful completion of the joint NBS-CGA

cryogenic flow measurement program which has resulted in the adoption of

a cryogenic flow measurement code by the National Conference on Weights

and Measures. We wish to extend this code on an international basis.

d) To establish and maintain the leadership of U.S. science, engineering,

and industry in the research, technology, manufacture and marketing of

instruments and measurement systems for liquefied natural gas.

6. Background . OIML was founded in 1955 to promote intergovernmental

cooperation in the field of legal metrology which relates to the com- patibility of standards of measurement and the legislation and government

regulations which may affect such standards of measurement. OIML

recommends uniform international requirements for scientific and measurement instruments used in industry and commerce and works out model laws

and regulations for consideration by member nations; and, in addition, serves as a center of documentation and information exchange in legal

metrology. At present 43 nations are members of this intergovernmental

organization

.

The United States joined OIML in 1972 (the Senate by resolution of

August 11, 1972 gave its advice and consent to the accession of the U.S.

to the convention establishing OIML) . The responsibility for managing

U.S. participation in OIML was assigned to the Department of Commerce

29
and has since been delegated by the Department to the National Bureau of

Standards (NBS) . Under the general guidance of the Department of State

and the Secretary of Commerce, NBS is directly responsible for formulating and implementing U.S. policy towards OIML. U. S. participation in

the organization is deemed important for two reasons: First, to protect

and enhance some $1 billion worth of scientific and measurement instruments

exported each year by U. S. firms and to insure equity in the trade of

commodities measured by these instruments; and second, to maintain the

U.S. as the world leader in the field of metrology.

In the spring of 1975 at a meeting in Paris of the International Committee

of Legal Metrology, the French and U.S. representatives discussed the

possibility of creating a new Reporting Secretariat No. 13 on "Liquefied

Natural Gas (LNG) Measurement". The U. S. representative, W. E. Andrus

,

Jr. of NBS, agreed to explore the possibility with U. S. industry and

interested government agencies. These discussions resulted in a decision

to propose a joint Secretariat with the American Gas Association and

NBS-Cryogenics Division in order to best accomplish the tasks. These

conclusions were reached during several meetings extending through the

latter part of 1975 and early 1976.

7. Program and Results . During this reporting period, the primary objective

of the program has been organizational in nature. Douglas Mann of

NBS-Cryogenics Division was assigned as co-technical advisor by the

National Bureau of Standards. Mr. D. A. Tefankjian, Superintendent,

Measurement Department, Texas Eastern Transmission Corporation (the

official A. G. A. /OIML representative) has begun the process of selecting

an A.G.A. co-technical advisor.

8. Problem Areas . None.

9. Funding . January 1 - June 30, 1976. 10K$

10. Future Plans . A meeting is planned in late August of representatives

from the Cryogenics Division (NBS) , the Office of International Standards

(NBS), and representatives of the American Gas Assocation to define the

scope direction and time table for the accomplishment of the objectives.

30
Title . FEDERAL POWER COMMISSION CONSULTATION

Principal Investigators . D. B. Chelton, A. F. Schmidt and T. R. Strobridge.

Cost Center Number . 2750404

Sponsor . Federal Power Commission - Bureau of Natural Gas -- letter

agreement dated 4 June 1973.

Goals . The Cryogenics Division will provide consultation and advisory

services to the Federal Power Commission on the cryogenic safety and

the design aspects of current applications before the FPC for authorization of LNG terminal and storage facilities. These services cover

properties of cryogenic environments, insulation systems, cryogenic

safety, thermodynamics, heat transfer, instrumentation, and cryogenic

processes such as refrigeration and liquefaction.

Background . Cost Center initiated July 7, 1973.

Program and Results . The status of those facilities presently under

the jurisdiction of the Federal Power Commission and subject to our review are outlined in the following table.

Elements of the facilities that are subject to review are the landbased cryogenic storage tank components, bounded by the tanker or barg

the inlet and distribution pipelines. These include, but are not

limited to the transfer lines, the storage tanks, the vaporizers and

the process piping as it interacts with the storage tanks. It is

essential that the reviews cover the operation, maintenance and emer- gency procedural philosophies for each terminal. Based upon these

studies, reports are submitted to the staff of the FPC setting forth

the technical evaluations and conclusions on each proposal.

Emphasis is placed on the safety aspects of the facilities including

their possible interactions with the surrounding areas. The impact of

engineering design such as appropriate use of existing technology and

material selection for structural integrity must be assessed. The

basis of review includes various codes and standards, prior experience

precedent and engineering knowledge. Vapor cloud generation and plume

dispersion is considered a subject beyond our area of expertise.

Future Plans . At the present time there are several pending applications, but detailed information is not yet available. It is anticipated that additional facilities will be reviewed as applications are made to the Federal Power Commission.

Funding

.

FY 76

January 1 - June 30, 1976

Anticipated Man-years of Effort FY 76

35K$

20K$

0.5

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32
APPENDIX A

A-l
Fracture Behavior of the Heat Affected

Zone in 5% Ni Steel Weldments*

Harry I. McHenry and. Richard P. Reed

Cryogenics Division

Institute for Basic Standards

National Bureau of Standards

Boulder, Colorado 80302

Contribution of NBS, not subject to copyright.

A-2
ABSTRACT

The fracture properties of the base metal and the heat affected zone

(HAZ) of 5% Ni steel weldments were determined at room temperature, 111 K

and 76 K; emphasis was placed on tests at 111 K, the minimum boiling point

of liquefied natural gas (LNG) . The 32 mm-thick test plates, which met the

requirements of ASTM A645, were welded using the pulsed-power gas-metal-arc

process at a heat input of 10.6 kJ/cm. The fatigue crack growth rates were

determined for cracks growing through the thickness using four-point bend

specimens. At 111 K, the rates in the base metal were essentially the same

as found by other investigators; however, the rates in the HAZ were up to 10

times faster than previously reported. Fracture toughness tests were conducted under load-controlled conditions using J-integral procedures. At 111

K, the base metal and HAZ toughness values were 30 and 50 per cent lower,

respectively, than toughness values obtained previously for the same plate

of test material under displacement-controlled conditions. Fracture mechanics

analyses using the results reported herein indicate that 5% Ni steel is

suitable for LNG applications, but more conservative estimates of fatigue

life and critical crack size are necessary.

Key Words: Cryogenic temperature; fatigue crack growth; fracture toughness;

heat affected zone; J-integral; nickel steel; weldments.

A-3
INTRODUCTION

The international trade in liquefied natural gas (LNG) has created a

large market for equipment to transport, store and process LNG. Structural

materials used for these applications must have adequate strength and toughness at 111 K, the minimum boiling point of LNG. Presently, 9% Ni steel (ASTM

A353 and A553) and 5083-0 aluminum alloy are the most widely used materials

for LNG structural applications (1). However, a 5% Ni steel, which is specially heat treated to meet the requirements of ASTM specification A645,

offers significant cost savings potential and may be widely used in the future.

Over the past few years, considerable work has been done to characterize

5% Ni steel and its weldments at temperatures down to 76 K (2) . The fatigue

and fracture properties of the weldments have been evaluated by Sarno, Bruner

and Kampschaefer (3), Bucci, Greene and Paris (4) and Murayama, Pense and

Stout (5). The fatigue crack growth behavior in the heat affected zone (HAZ)

was found (3,4) to be far superior to the corresponding behavior in the base

metal. For example, at a stress intensity range, AK, of 40 MPav'm (36.1 ksi

/in) , the growth rates of cracks in the base metal were about 10 times faster

than that of cracks in the HAZ. The fracture toughness of the HAZ was

reported (3,4,5) to range between 88 and 526 MPav'm (79.4 to 475 ksi/in) over a

thickness range of 6.4 to 38mm; low values occurred in thick-section loadcontrolled tests (3) and the highest values occured in thin-section

displacement-controlled tests. This variation in toughness results in a 36-

fold difference in calculations of critical crack lengths.

The present study was undertaken to further investigate and clarify the

fracture behavior of 5% Ni steel weldments. Fatigue and fracture tests were

conducted on the HAZ and the base metal at room temperature, 111 K and 76 K.

Emphasis was placed on determining the relative contributions of material

variability and of test-method peculiarities to the range of results previously reported. The questions of principal interest are: (1) Is the

A-4
fatigue crack growth resistance of the HAZ really that good? and (2) Is

the toughness of the HAZ really that unpredictable? To answer these questions, two experimental objectives were established. First, the fatigue

crack growth behavior of a crack in the HAZ will be determined as it propagates through the thickness. In addition to being an important practical

case, cracks in this orientation do not benefit from the favorable closure

effects that may have influenced the previous results as discussed by

Bucci et al. (4) . Second, the range of fracture toughness in the HAZ will

be established under load-controlled conditions. A direct comparison with

the displacement-controlled toughness measured by Sarno et al. (3) will be

possible because the test weldment was prepared using 5% Ni steel from the

same heat and essentially the same welding procedures.

MATERIALS AND PROCEDURES

Test Weldments

Two 32 mm-thick 5% Ni steel plates were welded with Inconel 92* (AWS A

5.14 Class ERNiCrFe-6) filler wire. One of the test plates was oriented

with the rolling direction perpendicular to the weld joint. This enabled

evaluation of HAZ toughness in both base plate orientations. The chemical

composition and mechanical properties of the base plate as reported by

Sarno (6) are shown in Table I.

Welding was done by the Armco Steel Research Center using the pulsedpower gas-metal-arc process and the parameters summarized in Table II. The

weld-joint preparation and the welding sequence are shown in Figure 1.

Charpy impact tests were conducted to verify that the weldment met

the toughness requirements established by the U.S. Coast Guard (7) for LNG

service. Type A (V-notch) specimens were tested in accordance with ASTM E-23

*Tradenames are used in this report for clarity; in no way does this imply

recommendation or endorsement by the National Bureau of Standards, nor does

it imply that the material is the best available for the purpose.

A5
at 76 K. The specimens were cut transverse to the weld axis with the

notches normal to the plate surface. The HAZ specimens were cut such that

the notch was in the base plate oriented with the rolling direction parallel

to the weld joint. Three specimens were tested for each of the following

locations as shown in Figure 2: centered in the weld metal; on the fusion

line; and in the HAZ 1, 3 and 5 mm from the fusion line. The results are

summarized in Table III.

Fatigue Crack Growth Specimens

The fatigue crack growth tests were conducted using four point bend

specimens as shown in Figure 3. This specimen was selected to enable determination of the fatigue crack growth rates in the L T orientation, i.e. the

plate is loaded in the transverse direction and the crack propagates through

the thickness.

A compliance calibration, needed for crack length measurements in the

fatigue tests, was established for the four-point bend specimen. Compliance

C, is the ratio of crack opening displacement, A, to applied load, P; and C

is a function of crack length, a, specimen geometry, and the elastic modulus

of the material, E:

where B = specimen thickness, W = specimen width, and f(rr) = compliance funcw tion. The compliance calibration, EBC vs a/W, was obtained using a single

specimen by progressively extending a fatigue crack into the specimen and

measuring compliance at growth increments of approximately 1 mm. After each

compliance measurement, the ratio of minimum-to-maximum load, R, was changed

to either R = 0.1 or R = 0.5. An ASTM E-399 clip gage was used for A measurements. At a crack length of 1.81 cm, the specimen was fractured to expose the

A-6
fatigue bands corresponding to each increment of crack growth. Crack lengths

for each compliance measurement point were measured from a photograph, Figure

A, of the fracture surface. An average value of the mid-thickness and two

quarter- thickness readings was used as the crack length.

The results of the compliance calibration test are shown in Figure 5. A

least-squares best fit analysis of the data yields the following expression:

1. 1, 1/ a = W[0.5332 - 1.863(EBC) X 6 + 1.641(EBC) ' 3 - . 3525 (EBC) ' 2] t (2)

for 0.2 < a/W < 0.6. The agreement of Equation (1) with the experimental data

and the theoretical results of Srawley and Gross (9) is shown in Figure 5.

Fatigue Crack Growth Testing

Fatigue crack growth tests were conducted on the base metal and the HAZ

in air at room temperature, in nitrogen vapor at 111 K and in liquid nitrogen

at 76 K. Two tests at 76 K were also conducted on the weld metal. The LNG

temperature of 111 K was maintained within + 3 K by adjusting the flow of

liquid nitrogen into the test dewar with a hand-operated needle valve. Temperature was monitored with a type E thermocouple taped to the bottom of the

test specimen.

Four point bend specimens were mounted in the test fixture shown in

Figure 6 for fatigue testing in a 100 kN (22,480 lb) electrohydraulic fatigue

machine. Tests were conducted using a 20 Hz sinusoidal load wave at an R of

0.1. All specimens were precracked at room temperature to an initial crack

length of 0.611 cm (i.e. 0.311 cm beyond the machined-notch depth) using a

maximum load that was less than or equal to the maximum load for the fatigue

crack growth tests. The procedures for room and cryogenic testing were the

same except for the temperature control provisions.

The compliance method (9) was used for crack length measurements. Compliance measurements were taken at increments where the estimated growth
was 0.751 cm. The recorded data were cycle number and compliance. Crack

lengths were determined from the compliance calibration, Equation (1). Stress

intensity ranges, AK, were computed from the K-calibration equation of Gross

and Srawley (10):

(P - P . )Va

AK = ^

BW

Y (a/W) (3)

where,

Y(^) = 1.992 - 2.468(|) + 12.97(^)

2 - 23.17(|) 3 + 24.8(|)\ (4)

P = maximum load in the fatigue cycle and P . = minimum load in the max mxn

fatigue cycle. Crack growth rates were determined by the central difference

method. The results were presented in log-log plots of da/dN vs AK.

Fracture Toughness Testing

Fracture toughness tests were conducted on the base metal and the HAZ

in nitrogen vapor at 111 K. Additional tests were conducted on the HAZ in

air at room temperature and in liquid nitrogen at 76 K. The temperature of

111 K was maintained as in the fatigue tests except that the control thermocouple was mounted on the side of the specimen in the plane of the crack.

Modified compact specimens, Figure 7, were tested in accordance with

the J-integral procedures described by Landes and Begley (11) . In this

method, each specimen is loaded to a predetermined displacement level such

that a range of subcritical crack extensions occurs in a given test series.

Upon reaching the predetermined displacement level, the specimen is unloaded,

heat tinted to mark the region of subcritical crack growth that occurred

during the load cycle and subsequently loaded to failure to expose the

fracture surfaces for measurements of crack length, a, and crack extension,

A-8
Aa. The J-integral value for the test is calculated using the approximation

of Rice, Paris and Merkle (12):

where A is the area under the load displacement curve. For a given test

series, a curve of J vs Aa is constructed. On the same graph, the line

defined by Equation (6) is drawn:

J = 2a,... Aa, (6) flow

where aci = (a + a )/2, a = .2% offset yield strength, and a , = flow ys uts ys uts

ultimate tensile strength. The intersection of the J-Aa plot and the J/^f-^ow

line is defined as JTr , the value of J at the onset of crack extension.

Apparent crack extension at Aa values less than J/2a^ ^ S attr ^ Dutec^ t0

deformation at the crack tip instead of material separation. Begley and

Landes (13) have proposed that the plane strain fracture toughness, Kj^> is

related to J as follows:

K

IC

(J) = (— '2 , (7)

where E = Young's modulus and V = Poisson's ratio.

Tests were conducted in two electrohydraulic fatigue machines, each

with 100 kN (22,480 lb) capacity. One machine employed the cryostat described

by Fowlkes and Tobler (14) , and the other a dewar equipped with the mechanical feedthrough shown in Figure 8. The specimens were loaded at 0.5 kN/s

(111 lb/s) under load control. Loading was continued until either failure,

A-9
crack extension due to pop-in, or a predetermined displacement was reached.

The specific test termination point for each test is noted in the results.

Specimens unloaded prior to failure were heat tinted and subsequently loaded

to failure at 76 K to expose the fracture surface. Tinting was accomplished

by heating the specimens in a 813 K furnace for 15 minutes. The fractured

surfaces were visually examined under 35X magnification for evidence of subcritical crack extension.

RESULTS AND DISCUSSION

Fatigue Crack Growth

The fatigue crack growth test results on 5% Ni steel weldments at

room temperature, 111 K and 76 K are summarized in Figures 9, 10 and 11,

respectively. The Paris power law (15), Equation (8), is used as the basis

for empirical analysis of the data:

§ = C(AK)

n

, (8)

where C is the intercept and n is the slope of a log-log plot of da/dn vs

AK. A least-squares regression analysis was used to obtain a statistical

fit of the crack growth data. For each test condition, values of C and n

are included in the appropriate plot of the results, Figures 9 to 11.

In all cases, the fatigue cracks propagated in a direction perpendicular

to the bending stress, i.e. local properties within the HAZ did not influence

the path followed by the fatigue crack. The location of the crack tip varied

from the fusion line to a distance about 7 mm from the fusion line as the

crack propagated through the thickness.

The fatigue crack growth data for the base metal and the HAZ at room

temperature are summaried in Figure 9. The growth rates are essentially the

A-10
same in both cases and coincide with the base metal data of Bucci et al. (4)

and of Tobler, Mikesell, Durcholz and Reed (16).

The fatigue crack growth data for the base metal and the HAZ at 111 K are

summarized in Figure 10. The base metal data are in good agreement with the

data of previous investigations (3,14,16). However, in contrast with previous

results (3,4) where the HAZ exhibited reduced growth rates, the growth rates

in the HAZ are approximately 1.5 times faster than the corresponding rates in

the base metal. The principal difference between the present and previous

investigations was crack orientation. In this study, growth rates were measured as the crack propagated through the thickness; in the previous studies,

through-thickness cracks were propagated in the rolling direction. The difference in crack orientation did not appear to influence the base metal

results - which were equivalent in all cases (3,14,16). However, in the

previous (3,4) HAZ tests, through- thickness cracks were partially located

(i.e. near both surfaces) in ductile weld metal. Apparently, deformation of

the weld metal limited the range of crack-opening-displacements in these tests

and resulted in reduced growth rates as discussed by Bucci et al. (4).

The fatigue crack growth data for the base metal, the HAZ and the weld

metal at 76 K are summarized in Figure 11. The base metal data overlap the

results of Tobler et al. (16), but have a slightly greater slope than the

results of Bucci et al. (4). The crack growth rate in the HAZ was significantly faster than that observed in the base metal. The weld metal had the

greatest resistance to fatigue crack growth at 76 K - the only temperature

where the crack growth behavior of the weld metal was determined. The crack

growth rates in the weld metal at low AK levels exhibited more scatter than

observed in the higher AK tests; however, growth was observed at AK levels

down to 15 MPav^n (13.5 ksi/in) . The lowest values of AK employed in the

A-ll
weld metal tests of Sarno et al. (3) were approximately 30 MPa/m (27.1 ksi

/in); difficulties were encountered in getting uniform crack growth along the

crack front at lower stress intensities. Similarly, Bucci et al. (A) found it

difficult to sustain crack growth in the weld metal at AK levels less than AO

MPa^m (36.1 ksi/in) .

The temperature dependence of fatigue crack growth in 5% Ni weldments is

summarized in Figure 12. The room temperature and 111 K data tend to be

approximately the same. A significant increase in growth rates occurred at 76

K, particularly in the HAZ tests. The relatively strong temperature dependence between 111 and 76 K may be due to the large decrease in fracture toughness that occurs over this same temperature range (16)

.

Some crack growth retardation was observed in the present study. In each

of the HAZ tests conducted at a maximum load of 6 kN (1350 lb) (specimens 8,

A, 5 and 6), retardation was exhibited at stress intensity levels of over 30

MPav^n (27.1 ksiv^n) , i.e. at crack lengths in excess of a/W = 0.5. Examination

of the load-displacement curves for these data points suggest that the reduced

growth rates may have been due to crack closure effects. The data points that

may have been influenced by closure effects are plotted in Figure 9 to 11;

however, these data were not included in the regression analysis to determine

C and n values. Similar retardation effects were not observed in the higher

load tests (P > 6 kN) , probably because net section yielding tended to max

separate the fracture surfaces at crack depths greater than a/W = 0.5.

Fracture Toughness

The fracture toughness data for 5% Ni steel weldments at room temperature, 111 K and 76 K are summarized in Table IV. Tests at room temperature

and 76 K were conducted on the HAZ in the transverse (TL) orientation. Tests

at 111 K were conducted on the base metal in the TL orientation and on the HAZ

in both the longitudinal (LT) and TL orientations. Tests were

A-12
not conducted on the nickel-base weld metal because it was assumed to be

tougher than the parent metal or the HAZ on the basis of the Charpy impact

results of Table III.

Emphasis was placed on determining the range of fracture toughness

characteristic of the HAZ at 111 K. The upper-bound was established by

the base metal toughness which averaged 159 MPav'in (144 ksi/in) in the two

specimens that were loaded to failure; the specimens unloaded prior to

failure are discussed below. A lower bound was established by measuring

the fracture toughness at pop-in. Pop-in is an abrupt sub-critical crack

extension that causes a discontinuity in the load-displacement curve -

usually a sudden increase in displacement at a fixed or decreasing load.

Three TL specimens exhibited pop-in at an average toughness of 108 MPav'm

(97.5 ksi/in) and one LT specimen exhibited a pop-in at 136 MPav'm (123 ksi/in) .

In each test where pop-in occurred, the specimen was unloaded immediately after

pop-in, heat tinted, fractured and visually examined to identify the location

in the HAZ where pop-in occurred. The fracture surfaces of the four specimens that exhibited pop-in are shown in Figure 13. In each case, pop-in

occurred along the crack front from the fusion line to a location approximately

corresponding to the 5 mm line of Figure 2. Thus, the lowest toughness

region of the weldment was identified as the HAZ, but within the HAZ the

location of minimum toughness could not be identified. The HAZ toughness was

greater in the LT orientation, averaging 155 MPa/m (140 ksi/in) than in the

TL orientation which averaged 131 MPav'm (118 ksi/in).

The HAZ of 5% Ni weldments exhibited relatively brittle behavior at

76 K and very tough behavior at room temperature. The toughness at 76 K

averaged 77 MPav'm (69.5 ksi/in). Three of the five tests at 76 K satisfied

the thickness requirements of ASTM Standard E-399 for valid K measurements.

A-13
The toughness of the HAZ at room temperature could not be estimated on the

basis of the four tests conducted because subcritical crack growth occurred

in only one test. The results do suggest that the HAZ toughness is at least

as good as the base metal toughness of 220 MPa^m (200 ksi/in) reported by

Tobler et al. (16) for a test plate from the same heat of 5% Ni steel.

In the fracture toughness tests, efforts were made to obtain J-Aa data

for Kj^(J) calculations as described in the procedure section. However,

subcritical crack extension was not detected (except in room temperature

test 3-1) prior to pop-in or fracture despite repeated efforts to find it.

In Table IV, each specimen with the note "-unloaded, no Aa-" was loaded to the

J level given, unloaded, heat tinted, fractured, and visually examined at 35X

for evidence of subcritical crack extension; in each test as noted, no crack

extension was observed. Apparently 5% Ni Steel (base metal and HAZ) does not

exhibit the slow tearing type of subcritical crack extension at temperatures

of 111 K and 76 K unless tested by the displacement-controlled R-curve method

used by Sarno et al. (3). Tobler et al. (16) did obtain J-Aa curves at room

temperature and 195 K, but did not report subcritical crack growth in the

111 K and 76 K tests.

The plane of the notch in the HAZ specimens is shown in the sketch of

the fracture toughness specimen, Figure 7. The fatigue precrack did not

propagate uniformly in the HAZ, growing faster on the outside than in the

center. The characteristic shape of the precrack, as shown in Figure 13, was

essentially the same in all HAZ tests. Crack lengths for fracture toughness

calculations were arbitrarily defined as the average of the two maximum lengths

at the outside and the minimum length in the center. The precracks in the

base metal tests were uniform, and the length was computed as the average of

the 1/4, 1/2 and 3/4 thickness values.

A-14
Care must be taken in comparing the present results with those obtained

by Sarno et al. (3) because of the differences in both the test method and

the definition of fracture toughness. Consider, for example, the 111 K

test results. In the present investigation, fracture toughness was determined for crack initiation conditions. For the base-metal, specimen failure

occurred prior to pop-in and the measured toughness is clearly indicative of

the fracture resistance of the material under load-controlled conditions.

However, in the HAZ tests, pop-in generally occurred and the load and displacement at pop-in were used to determine the fracture toughness. In contrast, Sarno et al. measured fracture toughness under displacement-controlled

conditions in accordance with the ASTM proposed R-curve procedure (17).

Using these procedures, stable crack extension readily occurs prior to fracture and toughness is measured after considerable crack extension has occurre

Since toughness increases following the initial increments of crack extension

the fracture toughness values determined by this method are higher. In the

HAZ tests on 38 mm plate, Sarno (18) observed pop-in at approximately 110

MPav'm (100 ksi/in) which is essentially the same as the value reported herein

However, the test was continued until the full fracture resistance curve was

developed and a higher value of fracture toughness (217 MPa^m) was reported.

Thus, the differences in fracture toughness results are attributable primarily to test method and not to material variability. Comments on the

significance of these differences from a design standpoint are included

in the next section.

A-15
IMPLICATIONS OF THE TEST RESULTS

The test data generated in this program indicate that for the conditions

evaluated the fracture resistance of 5% Ni steel weldments may be significantly lower than expected on the basis of previous investigations (3,4). In

this section, the significance of the present results relative to LNG applications is assessed.

The fatigue crack growth rates in the HAZ for cracks growing through the

thickness are 3 to 10 times faster than the rates reported by Sarno et al. (3)

for through- thickness cracks growing in the rolling direction. Consideration

is given here to how these results influence life assessments based on fracture mechanics analysis. McCabe, Sarno and Feddersen (19) computed the number

of fatigue cycles required to propagate an initial surface crack (semi-elliptica

shape, 4 mm deep and 16 mm long) through the thickness of a 16 mm thick plate

of 5% Ni steel at 103 K. The fatigue cycling conditions and the stress levels

were appropriate for a semi-membrane tank in an LNG ship. Their analysis used

the best-fit data of Sarno et al. (3) for the base metal at 103 K as shown in

Figure 10. The results indicated that, assuming no crack growth retardation,

the fatigue life of the initial flaw prior to leakage was approximately 192

years. In this analysis, it was appropriate to use base metal data, because

the crack growth rates were lower in the HAZ. The present results indicate

that the growth rates are greater in the HAZ than in the base metal; however,

the average rates in the HAZ still fall within the scatterband for the base

metal defined by Sarno et al. (3) and within the variability normally found in

fatigue crack growth testing (20). The upperbound line of Sarno et al. (3) is

a factor of 2.5 greater than the best-fit line used in the analysis (19),

i.e. the slope n of equation (8) is the same but the C value is 2.5 times

greater. Use of the upper-bound crack growth data would conservatively account

for the increased growth rates observed in the HAZ in the present study.

Since life scales linearly with C, a conservative estimate of life based on the

A-16
analysis of McCabe et al. (19) but using the present HAZ crack growth rates

would be 77 years. Clearly, this life is sufficient for safe operation of

LNG ships for their intended period of use is less than 30 years.

At 111 K the fracture toughness of the HAZ in the present study averaged

108 MPa/n at pop- in. In contrast, the HAZ toughness reported by Sarno et al.

(3) under displacement-controlled conditions was 217 MPa»/m (196 ksi/in) for

38 mm thick plate. The displacement-controlled toughness should be appropriate for redundant structures, but not for single load path structures such

as storage tanks and the spherical shipboard tanks of the Moss-Rosenberg (21)

design. The displacement-controlled toughness is a factor of 2 greater than

the load-controlled toughness. Since critical crack size scales as the squar

of fracture toughness, a four-fold decrease in critical crack size occurs

under load-controlled conditions. Thus, the critical crack size of 102 cm

calculated by Sarno et al. (3) for a stress of 163 MPa (23.7 ksi) would be

reduced to 25 cm for the present results . Measurements by Tenge and Solli

(22)

indicate that leaks are detectable at crack lengths of 2 to 4 cm on the penetrating side. Thus, there appears to be a reasonable margin of safety on

critical crack size for the load-control case.

The preceding discussion suggests that the failure resistance of 5% Ni

steel weldments is satisfactory for LNG applications. This is true for the

uniform stress conditions evaluated. Further analyses are required to demonstrate structural safety for cases of combined membrane plus bending stresses

For combined loading, stress levels as high as 378 MPa (55 ksi) are permitted

by the U.S. Coast Guard (23). These higher stresses will result in faster

crack growth rates and shorter critical sizes. In addition, the bending component will cause cracks to grow preferentially along the high tension surfac

resulting in cracks that are much longer at the time of initial leakage.

Assuming leakage still occurs prior to fracture, there is less time available

A-17
for detecting the leak and taking preventive action than there would be for

shorter cracks.

The results of the present investigation are also useful in deciding

whether or not to substitute 5% Ni steel for 9% Ni steel. Substitution

appears to be satisfactory for LNG applications where the service temperature

is approximately 111 K. However, in liquid nitrogen at 76 K, the 5% Ni steel

weldments exhibit brittle behavior and should not be used in place of 9% Ni

steel which retains a higher level of toughness (1,5,16). Since the scope of

the current study was limited to evaluation of a single weldment of 32 mm

plate, care should be taken in using these data to justify selection of 5% Ni

steel.

SUMMARY AND. CONCLUSIONS

The fatigue crack growth behavior and the fracture toughness of 32 mmthick 5% Ni steel weldments have been determined at room temperature, 111 K

and 76 K.

The fatigue crack growth rates were determined for cracks propagating

through the thickness. In this orientation the crack growth rates in the

base metal are essentially the same as previously reported for throughthickness cracks growing in the rolling direction. However, in contrast to

previous results, the crack growth rates are faster in the HAZ than in the

base metal, particularly at the lower temperatures.

Fracture toughness tests were conducted under load-controlled conditions using test material from the same heat of 5% Ni steel previously

evaluated using controlled-displacement test conditions. In this investigation, the fracture toughness of the base metal at 111 K in the TL orientation averaged 159 MPav^m (144 ksi/in) , as compared to a value of 226 MPav'm

(204 ksi/in) measured at 103 K in the controlled-displacement tests. The

fracture toughness of the HAZ ranged from 103 to 145 MPav^ (93 to 131 ksi/in)

A-18
at 111 K, as compared to a value of 216 UPa/m (195 ksiv^n) in the controlled

displacement test. The differences in toughness were attributed to differences in the test methods employed and not to material variability.

The fatigue and fracture results reported herein suggest that 5% Ni

steel is suitable for LNG applications, but more conservative estimates of

life and critical crack size are in order. For the case of a semi-membrane

tank subject to uniform membrane stresses, the estimated life prior to leakage and critical crack size are reduced by factors of 2.5 and 4, respectively,

from values previously reported.

ACKNOWLEDGMENTS

This work was sponsored by the U.S. Maritime Administration; Mr. J. H.

Seelinger was the project monitor.

The authors wish to thank D. A. Sarno and J. P. Bruner of the Armco

Steel Company for providing the test weldment and the base metal characterization data. Appreciation is also expressed for R. L. Durcholz of NBS who

designed and fabricated the test dewar and R. L. Tobler, NBS, for critical

review of this manuscript.

A-19
REFERENCES

1. Properties of Materials for Liquefied Natural Gas Tankage, ASTM STP

579, American Society for Testing and Materials 1975.

2. Pense, A. W. and Stout, R. D. , "Fracture Toughness and Related Characteristics of the Cryogenic Nickel Steels," WRC Bulletin No. 205,

Welding Research Council, May 1975.

3. Sarno, D. A., Bruner, J. P. and Kampschaef er , G. E. , "Fracture Toughness

of 5% Nickel Steel Weldments," Welding Journal, Vol. 53 (11), Nov. 1974,

Res. Suppl. pp. 486-s to 494-s.

4. Bucci, R. J., Greene, B. N. and Paris, P. C. , "Fatigue Crack Propagation

and Fracture Toughness of 5 Nickel and 9 Nickel Steels at Cryogenic

Temperatures," Progress in Flaw-Growth and Fracture Toughness Testing,

ASTM STP 536, 1973, pp. 202-228.

5. Murayama, N. , Pense, A. W. and Stout, R. D. , "The Fracture Toughness of

Cryogenic Steels," Advances in Cryogenic Engineering, Vol. 22, 1976.

6. Sarno, D. A., Chemical, Mechanical Property and Weldability Data of Armco

CRYONIC 5 Steel, Armco Steel Company, June 1973.

7. Anon, U.S. Coast Guard Marine Engineering Regulations, Subchapter F,

CG-115, July 1970.

8. Srawley, J. E. and Gross, B. , "Stress Intensity Factors for Bend and

Compact Specimens," Engineering Fracture Mechanics, Vol. 4, 1972,

pp. 587-589.

9. McHenry, H. I., "A Compliance Method for Fatigue Crack Growth Studies

at Elevated Temperatures," Journal of Materials, Vol. 6 (4), 1971,

pp. 862-873.

10. Gross, B., Srawley, J. E. and Brown, W. F. , Jr., "Stress Intensity Factors

for a Single-Edge-Notch Tension Specimen by Boundry Collocation of a

A-20
Stress Function," Technical Note D-2395, NASA, August 1964.

11. Landes, J. D. and Begley, J. A., "Test Results from J-Integral Studies -

An Attempt to Establish a J Testing Procedure, " Fracture Analysis,

J- ASTM STP 560, 1975, pp. 170-186.

12. Rice, J. R., Paris, P. C. and Merkle, J. G. , "Some Further Results of

J-Integral Analysis and Estimates," Progress in Flaw-Growth and Fracture

Toughness Testing , ASTM STP 536, 1973, pp. 231-245.

13. Begley, J. A. and Landes, J. D. , "The J-Integral as a Fracture Criterion,"

Fracture Toughness , ASTM STP 514, 1972, pp. 1-20.

14. Fowlkes, C. W. and Tobler, R. L. , "Fracture Testing and Results for a

Ti-6A1-4V Alloy at Liquid Helium Temperature," Engineering Fracture

Mechanics, in Press.

15. Paris, P. C, "The Fracture Mechanics Approach to Fatigue," Proceedings ,

Tenth Sagamore Army Materials Research Conference , Syracuse University

Press, Syracuse, NY, 1964, pp. 107-127.

16. Tobler, R. L., Mikesell, R. P., Durcholz, R. L. and Reed, R. P., "Low

Temperature Fracture Behavior of Iron-Nickel Alloy Steels," Ref. 1,

pp. 261-287.

17. Anon., Proposed Recommended Practice for R-Curve Determination, 1974

Annual Book of ASTM Standards, American Society for Testing and

Materials, Philadelphia, PA, 1974.

18. Sarno, D. A., Armco Steel Corporation, Middletown, OH, Private communication, 1976.

19. McCabe, D. E., Sarno, D. A. and Feddersen, C. E. , "Fatigue Crack Growth

Rate Studies of Partial Thickness Cracks in ASTM Method A645-74 5 Percent

Nickel Steel," Ref. 1, pp. 238-260.

A-21
20. Clark, W. G . , Jr. and Hudak, S. J. Jr., "Variability in Fatigue Crack

Growth Rate Testing," Scientific Paper 74-1E7-MSLRA-P2 , Westinghouse

Research Laboratories, Pittsburgh, PA, September 18, 1974.

21. Howard, J. L., "LNG Marine Carrier Construction," Marine Technology,

Vol. 9 (3), 1972, pp. 281-291.

22. Tenge, P. and Solli, 0., "Fracture Mechanics in the Design of Large

Spherical Tanks for Ship Transport of LNG," Norwegian Maritime Research,

Vol. 1 (2), 1973, pp. 1-18.

23. Henn, A. E. and Dickey, T. R. , "New Regulations for Liquefied Gas

Carriers," paper presented at GASTECH 75, Paris, 1975.

24. Weston, W. F. , Naimon, E. R. and Ledbetter, H. M. , "Low Temperature

Elastic Properties of Aluminum 5083-0 and Four Ferritic Nickel Steels,"

Ref. 1, pp. 397-420.

A-22
LIST OF FIGURES

Fie

.

1. Weld "joint preparation and welding sequence.

Fie

.

2. Noteli locations for Charpy impact specimens.

Fie

.

o 3. Four point bend specimen for fatigue crack growth tests. '

Fie

.

4. Fracture surface of the compliance calibration specimen. (Scale in cm)

Fie

.

* -"-6 • 5. Compliance calibration of the four point bend specimen.

Fie

.

6. Four Doint bend te^t fixture

Fie

.

7. Modified compact specimen showing notch location for HAZ tests.

Fie

.

8. Mechanical feedthrough for test dewar.

Fie

.

9

.

Fatigue crack growth behavior of 5% Ni steel weldments at room

temperature

.

Fie

.

10. Fatigue crack growth behavior of 5% Ni steel weldments at 111 K.

Fie

.

11. Fatigue crack growth behavior of 5% Ni steel weldments at 76 K.

Fig. 12. Effect of temperature on the fatigue crack growth rates in 5% Ni

steel weldments.

Fig. 13. Fracture surfaces of the HAZ specimens that exhibited pop-in at 111 K,

A-23
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A-24
Table II. Welding Procedures

Weld position

Plate thickness

Joint design

Shielding gas

Interpass temp

No. of passes

Wire diameter

Horizontal

32 mm

Double vee (See Figure 1

75He-25Ar at 39 1/s

38 C°max.

21

1.1 mm

Parameters:

Current, DCRP, A

Voltage, V

Travel , mm/sec (ipm)

Pass 1 no

30

3.4(8)

Pass 2

140

32

5.1(12)

Passes 3-21

140

32

4.2(10)

Heat input, kJ/cm (kJ/in) 9.8(24.8) 8.8(22.4) 10.6(26.9)

A-25
Table III. Results of the Charpy V-notch impact tests

Notch Location Absorbe'd Energy

(See Figure 2) Individual Tests Average

J J (Ft lb)

Weld metal Failed to break (FTB) FTB

Fusion line 109, 91, 91 97(71)

HAZ, 1 mm 159, 91, 126 125(92)

HAZ, 3 mm 113, 31 , FTB 88(65)

HAZ, 5 mm 84, 54, 94 77(57)

A-26
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A-27
—i

—

Dimensions in mm

Fig. 1. Weld joint preparation and welding sequence.

A-28
Centerline of Weld

Fusion Line

1mm from Fusion Line

',, 3mm from Fusion Line

HAZ, 5mm from Fusion Line

Specimen A

Centerline N

T= 32mm

Fig. 2. Notch locations for Charpy impact specimens.

A-29
Centerline

of Weld

HAZ r Base Metal

Notch

Centerline

NOTCH LOCATIONS NOTCH DETAIL

HAZ Specimen

--< 250 >- 13

203 »

Y

130

i — 51 —

Dimensions in mm

Four point bend specimen for fatigue crack growth tests,

A-30
Fig. 4. Fracture surface of the compliance calibration specimen. (Scale in cm)

A-31
Compliance calibration of the four point bend specimen.

A-32
A-33
64

Dimensions in mm

Modified compact specimen showing notch location for HAZ tests.

A-34

A- b-B45
A-35
-2 —i—

BASE METAL

C=2.58x10- 8

n=2.49

O Spec 10

Pmax = 8 kN

I I I I l± TTT —i—i—i

i 1 1 m

COMPARISON

C=4.14x10" 8

n=2.36

- O Spec 8

Pmax=6 kN

Spec 3

Pmax = 11

HA2

Base Metal —

/ ^Bucci et al. (4)

Base Metal _

10 20 40 80 20 40 80

AK, MPe^/m"

20 40 80

Fatigue crack growth behavior of 5% Ni steel weldments at room temperature.

A-36
Fig. 10. Fatigue crack growth behavior of 5% Ni steel weldments at 111 K.

A-37
O O

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A-38
A-39
A-40
NBS-1 14A (REV. 7-73)

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLIC ATION OR REPORT NO. NBSIR 76-843 /£

2. Gov't Accession

No.

3. Recipient's Accession No.

4. TITLE AND SUBTITLE

LIQUEFIED NATURAL GAS RESEARCH AT THE NATIONAL BUREAU OF

STANDARDS

5. Publication Date January 1-June 30, 1976

6. Performing Organization Code

7. AUTHOR(S)

D. E. Diller, Editor

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No. 2750104

11. Contract/Grant No.

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

Same as Item #9.

13. Type of Report & Period Covered Semi-Aimual —

January 1-June 30, 1976

14. Sponsoring Agency, Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less [actual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here.) Twenty- two cost centers, supported by six other agency sponsors in addition to

NBS, provide the basis for liquefied natural gas (LNG) research at NBS. During this

six month reporting period the level of effort was at a 20 man-year level with funding expenditures of over $600,000. This integrated progress report to be issued in

January and July is designed to:

1) Provide all sponsoring agencies with a semi-annual and annual report on

the activities of their individual programs.

2) Inform all sponsoring agencies on related research being conducted at the

Cryogenics Division of NBS-IBS.

3) Provide a uniform reporting procedure which should maintain and improve

communication while minimizing the time, effort and paperwork at the cost

center level.

The contents of this report will augment the quarterly progress meetings of some sponsors, but will not necessarily replace such meetings. Distribution of this document is limited and intended primarily for the supporting agencies. Data or other

information must be considered preliminary, subject to change and unpublished; and

therefore not for citation in the open literature .

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons

)

Cryogenics; liquefied natural gas; measurement; methane; properties; research.

18. AVAILABILITY |

! Unlimited

[ X' For Official Distribution. Do Not Release to NTIS

I

1 Order From Sup. of Doc, U.S. Government Printing Office Washington, D.C. 20402, SD Cat. No. CH

I

^ Order From National Technical Information Service (NTIS)

Springfield, Virginia 22151

19. SECURITY CLASS

(THIS REPORT)

UNCLASSIFIED

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

21. NO. OF PAGES

22. Price

USCOMM-DC 29042-P74